diff --git a/extensions/cornerstone/src/Viewport/Overlays/CustomizableViewportOverlay.tsx b/extensions/cornerstone/src/Viewport/Overlays/CustomizableViewportOverlay.tsx
index 5a01b3525..9436c1fa3 100644
--- a/extensions/cornerstone/src/Viewport/Overlays/CustomizableViewportOverlay.tsx
+++ b/extensions/cornerstone/src/Viewport/Overlays/CustomizableViewportOverlay.tsx
@@ -39,11 +39,82 @@ interface OverlayItemProps {
 }
 
 const OverlayItemComponents = {
+  'ohif.overlayItem': OverlayItem,
   'ohif.overlayItem.windowLevel': VOIOverlayItem,
   'ohif.overlayItem.zoomLevel': ZoomOverlayItem,
   'ohif.overlayItem.instanceNumber': InstanceNumberOverlayItem,
 };
 
+
+const studyDateItem = {
+  id: 'StudyDate',
+  customizationType: 'ohif.overlayItem',
+  label: '',
+  title: 'Study date',
+  condition: ({ referenceInstance }) => referenceInstance?.StudyDate,
+  contentF: ({ referenceInstance, formatters: { formatDate } }) => formatDate(referenceInstance.StudyDate),
+};
+
+const seriesDescriptionItem = {
+  id: 'SeriesDescription',
+  customizationType: 'ohif.overlayItem',
+  label: '',
+  title: 'Series description',
+  condition: ({ referenceInstance }) => {
+    return referenceInstance && referenceInstance.SeriesDescription;
+  },
+  contentF: ({ referenceInstance }) => referenceInstance.SeriesDescription
+};
+
+const topLeftItems = { id: 'cornerstoneOverlayTopLeft', items: [studyDateItem, seriesDescriptionItem] };
+
+const topRightItems = { id: 'cornerstoneOverlayTopRight', items: [] };
+
+const bottomLeftItems = {
+  id: 'cornerstoneOverlayBottomLeft', items: [
+    {
+      id: 'WindowLevel',
+      customizationType: 'ohif.overlayItem.windowLevel',
+    },
+    {
+      id: 'ZoomLevel',
+      customizationType: 'ohif.overlayItem.zoomLevel',
+      condition: (props) => {
+        const activeToolName = props.toolGroupService.getActiveToolForViewport(props.viewportId);
+        return activeToolName === 'Zoom';
+      },
+    },
+  ]
+};
+
+const bottomRightItems = {
+  id: 'cornerstoneOverlayBottomRight',
+  items: [
+    {
+      id: 'InstanceNumber',
+      customizationType: 'ohif.overlayItem.instanceNumber',
+    },
+  ]
+};
+
+/**
+ * The @ohif/cornerstoneOverlay is a default value for a customization
+ * for the cornerstone overlays.  The intent is to allow it to be extended
+ * without needing to re-write the individual overlays by using the append
+ * mechanism.  Individual attributes can be modified individually without
+ * affecting the other items by using the append as well, with position
+ * based replacement.
+ * This is used as a default in the getCustomizationModule so that it
+ * is available early for additional customization extensions.
+ */
+const CornerstoneOverlay = {
+  id: '@ohif/cornerstoneOverlay',
+  topLeftItems,
+  topRightItems,
+  bottomLeftItems,
+  bottomRightItems,
+};
+
 /**
  * Customizable Viewport Overlay
  */
@@ -60,32 +131,33 @@ function CustomizableViewportOverlay({
   viewportId: string;
   servicesManager: AppTypes.ServicesManager;
 }) {
-  const { cornerstoneViewportService, customizationService, toolGroupService } =
+  const { cornerstoneViewportService, customizationService, toolGroupService, displaySetService } =
     servicesManager.services;
   const [voi, setVOI] = useState({ windowCenter: null, windowWidth: null });
   const [scale, setScale] = useState(1);
   const { imageIndex } = imageSliceData;
 
-  const topLeftCustomization = customizationService.getModeCustomization(
-    'cornerstoneOverlayTopLeft'
-  );
-  const topRightCustomization = customizationService.getModeCustomization(
-    'cornerstoneOverlayTopRight'
-  );
-  const bottomLeftCustomization = customizationService.getModeCustomization(
-    'cornerstoneOverlayBottomLeft'
-  );
-  const bottomRightCustomization = customizationService.getModeCustomization(
-    'cornerstoneOverlayBottomRight'
-  );
+  // The new customization is 'cornerstoneOverlay', with an append or replace
+  // on the individual items rather than defining individual items.
+  const cornerstoneOverlay = customizationService.getCustomization('@ohif/cornerstoneOverlay');
+
+  // Historical usage defined the overlays as separate items due to lack of
+  // append functionality.  This code enables the historical usage, but
+  // the recommended functionality is to append to the default values in
+  // cornerstoneOverlay rather than defining individual items.
+  const topLeftCustomization = customizationService.getCustomization(
+    'cornerstoneOverlayTopLeft'
+  ) || cornerstoneOverlay?.topLeftItems;
+  const topRightCustomization = customizationService.getCustomization(
+    'cornerstoneOverlayTopRight'
+  ) || cornerstoneOverlay?.topRightItems;
+  const bottomLeftCustomization = customizationService.getCustomization(
+    'cornerstoneOverlayBottomLeft'
+  ) || cornerstoneOverlay?.bottomLeftItems;
+  const bottomRightCustomization = customizationService.getCustomization(
+    'cornerstoneOverlayBottomRight'
+  ) || cornerstoneOverlay?.bottomRightItems;
 
-  const instances = useMemo(() => {
-    if (viewportData != null) {
-      return _getViewportInstances(viewportData);
-    } else {
-      return null;
-    }
-  }, [viewportData, imageIndex]);
 
   const instanceNumber = useMemo(
     () =>
@@ -95,6 +167,23 @@ function CustomizableViewportOverlay({
     [viewportData, viewportId, imageIndex, cornerstoneViewportService]
   );
 
+  const displaySetProps = useMemo(() => {
+    const displaySets = getDisplaySets(viewportData, displaySetService);
+    if (!displaySets) {
+      return null;
+    }
+    const [displaySet] = displaySets;
+    const { instances, instance: referenceInstance } = displaySet;
+    return {
+      displaySets,
+      displaySet,
+      instance: instances[imageIndex],
+      instances,
+      referenceInstance,
+    };
+  }, [viewportData, viewportId, instanceNumber, cornerstoneViewportService]);
+
+
   /**
    * Updating the VOI when the viewport changes its voi
    */
@@ -150,8 +239,9 @@ function CustomizableViewportOverlay({
   }, [viewportId, viewportData, cornerstoneViewportService, element]);
 
   const _renderOverlayItem = useCallback(
-    item => {
+    (item, props) => {
       const overlayItemProps = {
+        ...props,
         element,
         viewportData,
         imageSliceData,
@@ -164,10 +254,6 @@ function CustomizableViewportOverlay({
           formatTime: formatDICOMTime,
           formatNumberPrecision,
         },
-        instance: instances ? instances[item?.instanceIndex] : null,
-        voi,
-        scale,
-        instanceNumber,
       };
 
       if (!item) {
@@ -182,8 +268,8 @@ function CustomizableViewportOverlay({
       } else {
         const renderItem = customizationService.transform(item);
 
-        if (typeof renderItem.content === 'function') {
-          return renderItem.content(overlayItemProps);
+        if (typeof renderItem.contentF === 'function') {
+          return renderItem.contentF(overlayItemProps);
         }
       }
     },
@@ -194,7 +280,7 @@ function CustomizableViewportOverlay({
       viewportId,
       servicesManager,
       customizationService,
-      instances,
+      displaySetProps,
       voi,
       scale,
       instanceNumber,
@@ -202,20 +288,26 @@ function CustomizableViewportOverlay({
   );
 
   const getContent = useCallback(
-    (customization, defaultItems, keyPrefix) => {
-      const items = customization?.items ?? defaultItems;
+    (customization, keyPrefix) => {
+      if (!customization?.items) {
+        return null;
+      }
+      const { items } = customization;
+      const props = {
+        ...displaySetProps,
+        formatters: { formatDate: formatDICOMDate },
+        voi,
+        scale,
+        instanceNumber,
+        viewportId,
+        toolGroupService,
+      };
+
       return (
         <>
           {items.map((item, index) => (
             <div key={`${keyPrefix}_${index}`}>
-              {item?.condition
-                ? item.condition({
-                    instance: instances ? instances[item?.instanceIndex] : null,
-                    formatters: { formatDate: formatDICOMDate },
-                  })
-                  ? _renderOverlayItem(item)
-                  : null
-                : _renderOverlayItem(item)}
+              {(!item?.condition || item.condition(props)) && _renderOverlayItem(item, props) || null}
             </div>
           ))}
         </>
@@ -224,104 +316,30 @@ function CustomizableViewportOverlay({
     [_renderOverlayItem]
   );
 
-  const studyDateItem = {
-    id: 'StudyDate',
-    customizationType: 'ohif.overlayItem',
-    label: '',
-    title: 'Study date',
-    condition: ({ instance }) => instance && instance.StudyDate,
-    contentF: ({ instance, formatters: { formatDate } }) => formatDate(instance.StudyDate),
-  };
-
-  const seriesDescriptionItem = {
-    id: 'SeriesDescription',
-    customizationType: 'ohif.overlayItem',
-    label: '',
-    title: 'Series description',
-    attribute: 'SeriesDescription',
-    condition: ({ instance }) => {
-      return instance && instance.SeriesDescription;
-    },
-  };
-
-  const topLeftItems = instances
-    ? instances
-        .map((instance, index) => {
-          return [
-            {
-              ...studyDateItem,
-              instanceIndex: index,
-            },
-            {
-              ...seriesDescriptionItem,
-              instanceIndex: index,
-            },
-          ];
-        })
-        .flat()
-    : [];
 
   return (
     <ViewportOverlay
-      topLeft={
-        /**
-         * Inline default overlay items for a more standard expansion
-         */
-        getContent(topLeftCustomization, [...topLeftItems], 'topLeftOverlayItem')
-      }
-      topRight={getContent(topRightCustomization, [], 'topRightOverlayItem')}
-      bottomLeft={getContent(
-        bottomLeftCustomization,
-        [
-          {
-            id: 'WindowLevel',
-            customizationType: 'ohif.overlayItem.windowLevel',
-          },
-          {
-            id: 'ZoomLevel',
-            customizationType: 'ohif.overlayItem.zoomLevel',
-            condition: () => {
-              const activeToolName = toolGroupService.getActiveToolForViewport(viewportId);
-              return activeToolName === 'Zoom';
-            },
-          },
-        ],
-        'bottomLeftOverlayItem'
-      )}
-      bottomRight={getContent(
-        bottomRightCustomization,
-        [
-          {
-            id: 'InstanceNumber',
-            customizationType: 'ohif.overlayItem.instanceNumber',
-          },
-        ],
-        'bottomRightOverlayItem'
-      )}
+      topLeft={getContent(topLeftCustomization, 'topLeftOverlayItem')}
+      topRight={getContent(topRightCustomization, 'topRightOverlayItem')}
+      bottomLeft={getContent(bottomLeftCustomization, 'bottomLeftOverlayItem')}
+      bottomRight={getContent(bottomRightCustomization, 'bottomRightOverlayItem')}
     />
   );
 }
 
-function _getViewportInstances(viewportData) {
-  const imageIds = [];
-  if (viewportData.viewportType === Enums.ViewportType.STACK) {
-    imageIds.push(viewportData.data[0].imageIds[0]);
-  } else if (viewportData.viewportType === Enums.ViewportType.ORTHOGRAPHIC) {
-    const volumes = viewportData.data;
-    volumes.forEach(volume => {
-      if (!volume?.imageIds || volume.imageIds.length === 0) {
-        return;
-      }
-      imageIds.push(volume.imageIds[0]);
-    });
+/**
+ * Gets an array of display sets for the given viewport, based on the viewport data.
+ * Returns null if none found.
+ */
+function getDisplaySets(viewportData, displaySetService) {
+  if (!viewportData?.data?.length) {
+    return null;
   }
-  const instances = [];
-
-  imageIds.forEach(imageId => {
-    const instance = metaData.get('instance', imageId) || {};
-    instances.push(instance);
-  });
-  return instances;
+  const displaySets = viewportData.data.map(datum => displaySetService.getDisplaySetByUID(datum.displaySetInstanceUID)).filter(it => !!it);
+  if (!displaySets.length) {
+    return null;
+  }
+  return displaySets;
 }
 
 const getInstanceNumber = (viewportData, viewportId, imageIndex, cornerstoneViewportService) => {
@@ -364,6 +382,7 @@ function _getInstanceNumberFromStack(viewportData, imageIndex) {
   return parseInt(instanceNumber);
 }
 
+
 // Since volume viewports can be in any view direction, they can render
 // a reconstructed image which don't have imageIds; therefore, no instance and instanceNumber
 // Here we check if viewport is in the acquisition direction and if so, we get the instanceNumber
@@ -411,6 +430,24 @@ function _getInstanceNumberFromVolume(
   }
 }
 
+function OverlayItem(props) {
+  const { instance, customization = {} } = props;
+  const { color, attribute, title, label, background } = customization;
+  const value = customization.contentF?.(props, customization) ?? instance?.[attribute];
+  if (value === undefined || value === null) {
+    return null;
+  }
+  return (
+    <div
+      className="overlay-item flex flex-row"
+      style={{ color, background }}
+      title={title}
+    >
+      {label ? (<span className="mr-1 shrink-0">{label}</span>) : null}
+      <span className="ml-1 mr-2 shrink-0">{value}</span>
+    </div>);
+}
+
 /**
  * Window Level / Center Overlay item
  */
@@ -423,7 +460,7 @@ function VOIOverlayItem({ voi, customization }: OverlayItemProps) {
   return (
     <div
       className="overlay-item flex flex-row"
-      style={{ color: (customization && customization.color) || undefined }}
+      style={{ color: customization?.color }}
     >
       <span className="mr-1 shrink-0">W:</span>
       <span className="ml-1 mr-2 shrink-0">{windowWidth.toFixed(0)}</span>
@@ -484,3 +521,5 @@ CustomizableViewportOverlay.propTypes = {
 };
 
 export default CustomizableViewportOverlay;
+
+export { CustomizableViewportOverlay, CornerstoneOverlay };
diff --git a/extensions/cornerstone/src/Viewport/Overlays/utils.ts b/extensions/cornerstone/src/Viewport/Overlays/utils.ts
index 54f164add..d8795f3b3 100644
--- a/extensions/cornerstone/src/Viewport/Overlays/utils.ts
+++ b/extensions/cornerstone/src/Viewport/Overlays/utils.ts
@@ -62,6 +62,12 @@ export function formatPN(name) {
   if (!name) {
     return '';
   }
+  if (typeof name === 'object') {
+    name = name.Alphabetic;
+    if (!name) {
+      return '';
+    }
+  }
 
   const cleaned = name
     .split('^')
diff --git a/extensions/cornerstone/src/getCustomizationModule.ts b/extensions/cornerstone/src/getCustomizationModule.ts
index 6952839d8..32da1bb6d 100644
--- a/extensions/cornerstone/src/getCustomizationModule.ts
+++ b/extensions/cornerstone/src/getCustomizationModule.ts
@@ -4,6 +4,7 @@ import DicomUpload from './components/DicomUpload/DicomUpload';
 import defaultWindowLevelPresets from './components/WindowLevelActionMenu/defaultWindowLevelPresets';
 import { colormaps } from './utils/colormaps';
 import { CONSTANTS } from '@cornerstonejs/core';
+import { CornerstoneOverlay } from './Viewport/Overlays/CustomizableViewportOverlay';
 
 const DefaultColormap = 'Grayscale';
 const { VIEWPORT_PRESETS } = CONSTANTS;
@@ -47,6 +48,7 @@ function getCustomizationModule() {
     {
       name: 'default',
       value: [
+        CornerstoneOverlay,
         {
           id: 'cornerstone.overlayViewportTools',
           tools,
diff --git a/extensions/default/src/getCustomizationModule.tsx b/extensions/default/src/getCustomizationModule.tsx
index 9f7153af2..75de9b03d 100644
--- a/extensions/default/src/getCustomizationModule.tsx
+++ b/extensions/default/src/getCustomizationModule.tsx
@@ -167,7 +167,6 @@ export default function getCustomizationModule({ servicesManager, extensionManag
         },
         {
           id: 'studyBrowser.sortFunctions',
-          merge: 'Append',
           values: [
             {
               label: 'Series Number',
diff --git a/platform/app/public/config/customization.js b/platform/app/public/config/customization.js
new file mode 100644
index 000000000..39696c9b0
--- /dev/null
+++ b/platform/app/public/config/customization.js
@@ -0,0 +1,276 @@
+/** @type {AppTypes.Config} */
+window.config = {
+  routerBasename: '/',
+  extensions: [],
+  modes: ['@ohif/mode-test'],
+  showStudyList: true,
+  // below flag is for performance reasons, but it might not work for all servers
+  maxNumberOfWebWorkers: 3,
+  showWarningMessageForCrossOrigin: false,
+  showCPUFallbackMessage: false,
+  strictZSpacingForVolumeViewport: true,
+  // filterQueryParam: false,
+
+  // Add some customizations to the default e2e datasource
+  customizationService: [
+    '@ohif/extension-default.customizationModule.datasources',
+    '@ohif/extension-default.customizationModule.helloPage',
+
+    {
+      id: '@ohif/cornerstoneOverlay',
+      // Append recursively, rather than replacing
+      merge: 'Append',
+      topRightItems: {
+        id: 'cornerstoneOverlayTopRight',
+        items: [
+          {
+            id: 'PatientNameOverlay',
+            // Note below that here we are using the customization prototype of
+            // `ohif.overlayItem` which was registered to the customization module in
+            // `ohif/extension-default` extension.
+            customizationType: 'ohif.overlayItem',
+            // the following props are passed to the `ohif.overlayItem` prototype
+            // which is used to render the overlay item based on the label, color,
+            // conditions, etc.
+            attribute: 'PatientName',
+            label: 'PN:',
+            title: 'Patient Name',
+            color: 'yellow',
+            condition: ({ instance }) => instance?.PatientName,
+            contentF: ({ instance, formatters: { formatPN } }) =>
+              formatPN(instance.PatientName) +
+              (instance.PatientSex ? ' (' + instance.PatientSex + ')' : ''),
+          },
+        ],
+      },
+
+      topLeftItems: {
+        items: {
+          // Note the -10000 means -10000 + length of existing list, which is
+          // much before the start of hte list, so put the new value at the start.
+          '-10000':
+          {
+            id: 'Species',
+            customizationType: 'ohif.overlayItem',
+            label: 'Species:',
+            color: 'red',
+            background: 'green',
+            condition: ({ instance }) =>
+              instance?.PatientSpeciesDescription,
+            contentF: ({ instance }) =>
+              instance.PatientSpeciesDescription +
+              '/' +
+              instance.PatientBreedDescription,
+          },
+        },
+      },
+    },
+  ],
+
+  defaultDataSourceName: 'e2e',
+  investigationalUseDialog: {
+    option: 'never',
+  },
+  dataSources: [
+    {
+      namespace: '@ohif/extension-default.dataSourcesModule.dicomweb',
+      sourceName: 'e2e',
+      configuration: {
+        friendlyName: 'StaticWado test data',
+        // The most important field to set for static WADO
+        staticWado: true,
+        name: 'StaticWADO',
+        wadoUriRoot: '/viewer-testdata',
+        qidoRoot: '/viewer-testdata',
+        wadoRoot: '/viewer-testdata',
+        qidoSupportsIncludeField: false,
+        imageRendering: 'wadors',
+        thumbnailRendering: 'wadors',
+        enableStudyLazyLoad: true,
+        supportsFuzzyMatching: false,
+        supportsWildcard: true,
+        singlepart: 'video,thumbnail,pdf',
+        omitQuotationForMultipartRequest: true,
+        bulkDataURI: {
+          enabled: true,
+          relativeResolution: 'studies',
+        },
+      },
+    },
+    {
+      namespace: '@ohif/extension-default.dataSourcesModule.dicomweb',
+      sourceName: 'local5000',
+      configuration: {
+        friendlyName: 'Static WADO Local Data',
+        name: 'DCM4CHEE',
+        qidoRoot: 'http://localhost:5000/dicomweb',
+        wadoRoot: 'http://localhost:5000/dicomweb',
+        qidoSupportsIncludeField: false,
+        supportsReject: true,
+        supportsStow: true,
+        imageRendering: 'wadors',
+        thumbnailRendering: 'wadors',
+        enableStudyLazyLoad: true,
+        supportsFuzzyMatching: false,
+        supportsWildcard: true,
+        staticWado: true,
+        singlepart: 'video',
+        bulkDataURI: {
+          enabled: true,
+          relativeResolution: 'studies',
+        },
+      },
+    },
+    {
+      namespace: '@ohif/extension-default.dataSourcesModule.dicomweb',
+      sourceName: 'docker',
+      configuration: {
+        friendlyName: 'Static WADO Docker Data',
+        name: 'DCM4CHEE',
+        qidoRoot: 'http://localhost:25080/dicomweb',
+        wadoRoot: 'http://localhost:25080/dicomweb',
+        qidoSupportsIncludeField: false,
+        supportsReject: true,
+        supportsStow: true,
+        imageRendering: 'wadors',
+        thumbnailRendering: 'wadors',
+        enableStudyLazyLoad: true,
+        supportsFuzzyMatching: false,
+        supportsWildcard: true,
+        staticWado: true,
+        singlepart: 'bulkdata,video,pdf',
+        bulkDataURI: {
+          enabled: true,
+          relativeResolution: 'studies',
+        },
+      },
+    },
+    {
+      namespace: '@ohif/extension-default.dataSourcesModule.dicomweb',
+      sourceName: 'ohif',
+      configuration: {
+        friendlyName: 'AWS S3 Static wado server',
+        name: 'aws',
+        wadoUriRoot: 'https://d33do7qe4w26qo.cloudfront.net/dicomweb',
+        qidoRoot: 'https://d33do7qe4w26qo.cloudfront.net/dicomweb',
+        wadoRoot: 'https://d33do7qe4w26qo.cloudfront.net/dicomweb',
+        qidoSupportsIncludeField: false,
+        imageRendering: 'wadors',
+        thumbnailRendering: 'wadors',
+        enableStudyLazyLoad: true,
+        supportsFuzzyMatching: false,
+        supportsWildcard: true,
+        staticWado: true,
+        singlepart: 'video,pdf',
+        bulkDataURI: {
+          enabled: true,
+          relativeResolution: 'studies',
+        },
+      },
+    },
+
+    {
+      namespace: '@ohif/extension-default.dataSourcesModule.dicomweb',
+      sourceName: 'ohif2',
+      configuration: {
+        friendlyName: 'AWS S3 Static wado secondary server',
+        name: 'aws',
+        wadoUriRoot: 'https://d28o5kq0jsoob5.cloudfront.net/dicomweb',
+        qidoRoot: 'https://d28o5kq0jsoob5.cloudfront.net/dicomweb',
+        wadoRoot: 'https://d28o5kq0jsoob5.cloudfront.net/dicomweb',
+        qidoSupportsIncludeField: false,
+        supportsReject: false,
+        imageRendering: 'wadors',
+        thumbnailRendering: 'wadors',
+        enableStudyLazyLoad: true,
+        supportsFuzzyMatching: false,
+        supportsWildcard: true,
+        staticWado: true,
+        singlepart: 'bulkdata,video',
+        // whether the data source should use retrieveBulkData to grab metadata,
+        // and in case of relative path, what would it be relative to, options
+        // are in the series level or study level (some servers like series some study)
+        bulkDataURI: {
+          enabled: true,
+          relativeResolution: 'studies',
+        },
+        omitQuotationForMultipartRequest: true,
+      },
+    },
+    {
+      namespace: '@ohif/extension-default.dataSourcesModule.dicomweb',
+      sourceName: 'ohif3',
+      configuration: {
+        friendlyName: 'AWS S3 Static wado secondary server',
+        name: 'aws',
+        wadoUriRoot: 'https://d3t6nz73ql33tx.cloudfront.net/dicomweb',
+        qidoRoot: 'https://d3t6nz73ql33tx.cloudfront.net/dicomweb',
+        wadoRoot: 'https://d3t6nz73ql33tx.cloudfront.net/dicomweb',
+        qidoSupportsIncludeField: false,
+        supportsReject: false,
+        imageRendering: 'wadors',
+        thumbnailRendering: 'wadors',
+        enableStudyLazyLoad: true,
+        supportsFuzzyMatching: false,
+        supportsWildcard: true,
+        staticWado: true,
+        singlepart: 'bulkdata,video',
+        // whether the data source should use retrieveBulkData to grab metadata,
+        // and in case of relative path, what would it be relative to, options
+        // are in the series level or study level (some servers like series some study)
+        bulkDataURI: {
+          enabled: true,
+          relativeResolution: 'studies',
+        },
+        omitQuotationForMultipartRequest: true,
+      },
+    },
+
+    {
+      friendlyName: 'StaticWado default data',
+      namespace: '@ohif/extension-default.dataSourcesModule.dicomweb',
+      sourceName: 'dicomweb',
+      configuration: {
+        name: 'DCM4CHEE',
+        wadoUriRoot: '/dicomweb',
+        qidoRoot: '/dicomweb',
+        wadoRoot: '/dicomweb',
+        qidoSupportsIncludeField: false,
+        supportsReject: false,
+        imageRendering: 'wadors',
+        thumbnailRendering: 'wadors',
+        enableStudyLazyLoad: true,
+        supportsFuzzyMatching: false,
+        supportsWildcard: true,
+        staticWado: true,
+        bulkDataURI: {
+          enabled: true,
+          relativeResolution: 'studies',
+        },
+      },
+    },
+    {
+      namespace: '@ohif/extension-default.dataSourcesModule.dicomjson',
+      sourceName: 'dicomjson',
+      configuration: {
+        friendlyName: 'dicom json',
+        name: 'json',
+      },
+    },
+    {
+      namespace: '@ohif/extension-default.dataSourcesModule.dicomlocal',
+      sourceName: 'dicomlocal',
+      configuration: {
+        friendlyName: 'dicom local',
+      },
+    },
+  ],
+  httpErrorHandler: error => {
+    // This is 429 when rejected from the public idc sandbox too often.
+    console.warn(error.status);
+
+    // Could use services manager here to bring up a dialog/modal if needed.
+    console.warn('test, navigate to https://ohif.org/');
+  },
+  hotkeys: [],
+};
diff --git a/platform/core/src/services/CustomizationService/CustomizationService.ts b/platform/core/src/services/CustomizationService/CustomizationService.ts
index 4323bf88e..4dd7d505a 100644
--- a/platform/core/src/services/CustomizationService/CustomizationService.ts
+++ b/platform/core/src/services/CustomizationService/CustomizationService.ts
@@ -318,9 +318,15 @@ export default class CustomizationService extends PubSubService {
   }
 
   public setGlobalCustomization(id: string, value: Customization, merge = MergeEnum.Replace): void {
+    const defaultCustomization = this.defaultCustomizations.get(id);
+    const globCustomization = this.globalCustomizations.get(id);
+    const sourceCustomization =
+      (globCustomization && cloneDeepWith(globCustomization, cloneCustomizer)) ||
+      defaultCustomization ||
+      {};
     this.globalCustomizations.set(
       id,
-      this.mergeValue(this.globalCustomizations.get(id), value, merge)
+      this.mergeValue(sourceCustomization, value, value.merge ?? merge)
     );
     this.transformedCustomizations.clear();
     this._broadcastGlobalCustomizationModified();
@@ -445,7 +451,7 @@ function findPosition(key, value, newList) {
   const { length: len } = newList;
 
   if (isNumeric) {
-    if (newList[(numVal + len) % len]) {
+    if (newList[numVal < 0 ? numVal + len : numVal]) {
       return { isMerge: true, position: (numVal + len) % len };
     }
     const absPosition = Math.ceil(numVal < 0 ? len + numVal : numVal);
diff --git a/platform/core/src/services/ServicesManager.ts b/platform/core/src/services/ServicesManager.ts
index 759a965f4..a73ff9a45 100644
--- a/platform/core/src/services/ServicesManager.ts
+++ b/platform/core/src/services/ServicesManager.ts
@@ -52,7 +52,7 @@ export default class ServicesManager {
         extensionManager: this._extensionManager,
       });
       if (service.altName) {
-        console.log('Registering old name', service.altName);
+        // TODO - remove this registration
         this.services[service.altName] = this.services[service.name];
       }
     } else {
diff --git a/platform/docs/docs/platform/services/ui/customization-service.md b/platform/docs/docs/platform/services/ui/customization-service.md
index 7142b57e8..e42d201aa 100644
--- a/platform/docs/docs/platform/services/ui/customization-service.md
+++ b/platform/docs/docs/platform/services/ui/customization-service.md
@@ -401,145 +401,68 @@ customizationService: [
 
 Below is the full example configuration of the customizable viewport overlay and the screenshot of the result overlay.
 
+There are working examples that can be run with:
+```
+set APP_CONFIG=config/customization.js
+yarn dev
+```
+
 ```javascript
-// this is one of the configuration files in `platform/app/public/config/*.js`
+// this is part of customization.js, an example customization dataset
 window.config = {
-  // ...
 
-  customizationService: {
-    cornerstoneOverlayTopLeft: {
-      id: 'cornerstoneOverlayTopLeft',
-      items: [
-        {
-          id: 'WindowLevel',
-          customizationType: 'ohif.overlayItem.windowLevel',
+   // This shows how to append to the customization data
+   customizationService: [
+    {
+      id: '@ohif/cornerstoneOverlay',
+      // Append recursively, rather than replacing
+      merge: 'Append',
+      topRightItems: {
+        id: 'cornerstoneOverlayTopRight',
+        items: [
+          {
+            id: 'PatientNameOverlay',
+            // Note below that here we are using the customization prototype of
+            // `ohif.overlayItem` which was registered to the customization module in
+            // `ohif/extension-default` extension.
+            customizationType: 'ohif.overlayItem',
+            // the following props are passed to the `ohif.overlayItem` prototype
+            // which is used to render the overlay item based on the label, color,
+            // conditions, etc.
+            attribute: 'PatientName',
+            label: 'PN:',
+            title: 'Patient Name',
+            color: 'yellow',
+            condition: ({ instance }) => instance?.PatientName,
+            contentF: ({ instance, formatters: { formatPN } }) =>
+              formatPN(instance.PatientName) +
+              (instance.PatientSex ? ' (' + instance.PatientSex + ')' : ''),
+          },
+        ],
+      },
+
+      topLeftItems: {
+        items: {
+          // Note the -10000 means -10000 + length of existing list, which is
+          // much before the start of hte list, so put the new value at the start.
+          '-10000':
+          {
+            id: 'Species',
+            customizationType: 'ohif.overlayItem',
+            label: 'Species:',
+            color: 'red',
+            background: 'green',
+            condition: ({ instance }) =>
+              instance?.PatientSpeciesDescription,
+            contentF: ({ instance }) =>
+              instance.PatientSpeciesDescription +
+              '/' +
+              instance.PatientBreedDescription,
+          },
         },
-        {
-          id: 'PatientName',
-          customizationType: 'ohif.overlayItem',
-          label: '',
-          color: 'green',
-          background: 'white',
-          condition: ({ instance }) =>
-            instance && instance.PatientName && instance.PatientName.Alphabetic,
-          contentF: ({ instance, formatters: { formatPN } }) =>
-            formatPN(instance.PatientName.Alphabetic) +
-            ' ' +
-            (instance.PatientSex ? '(' + instance.PatientSex + ')' : ''),
-        },
-        {
-          id: 'Species',
-          customizationType: 'ohif.overlayItem',
-          label: 'Species:',
-          condition: ({ instance }) =>
-            instance && instance.PatientSpeciesDescription,
-          contentF: ({ instance }) =>
-            instance.PatientSpeciesDescription +
-            '/' +
-            instance.PatientBreedDescription,
-        },
-        {
-          id: 'PID',
-          customizationType: 'ohif.overlayItem',
-          label: 'PID:',
-          title: 'Patient PID',
-          condition: ({ instance }) => instance && instance.PatientID,
-          contentF: ({ instance }) => instance.PatientID,
-        },
-        {
-          id: 'PatientBirthDate',
-          customizationType: 'ohif.overlayItem',
-          label: 'DOB:',
-          title: "Patient's Date of birth",
-          condition: ({ instance }) => instance && instance.PatientBirthDate,
-          contentF: ({ instance }) => instance.PatientBirthDate,
-        },
-        {
-          id: 'OtherPid',
-          customizationType: 'ohif.overlayItem',
-          label: 'Other PID:',
-          title: 'Other Patient IDs',
-          condition: ({ instance }) => instance && instance.OtherPatientIDs,
-          contentF: ({ instance, formatters: { formatPN } }) =>
-            formatPN(instance.OtherPatientIDs),
-        },
-      ],
+      },
     },
-    cornerstoneOverlayTopRight: {
-      id: 'cornerstoneOverlayTopRight',
-
-      items: [
-        {
-          id: 'InstanceNmber',
-          customizationType: 'ohif.overlayItem.instanceNumber',
-        },
-        {
-          id: 'StudyDescription',
-          customizationType: 'ohif.overlayItem',
-          label: '',
-          title: ({ instance }) =>
-            instance &&
-            instance.StudyDescription &&
-            `Study Description: ${instance.StudyDescription}`,
-          condition: ({ instance }) => instance && instance.StudyDescription,
-          contentF: ({ instance }) => instance.StudyDescription,
-        },
-        {
-          id: 'StudyDate',
-          customizationType: 'ohif.overlayItem',
-          label: '',
-          title: 'Study date',
-          condition: ({ instance }) => instance && instance.StudyDate,
-          contentF: ({ instance, formatters: { formatDate } }) =>
-            formatDate(instance.StudyDate),
-        },
-        {
-          id: 'StudyTime',
-          customizationType: 'ohif.overlayItem',
-          label: '',
-          title: 'Study time',
-          condition: ({ instance }) => instance && instance.StudyTime,
-          contentF: ({ instance, formatters: { formatTime } }) =>
-            formatTime(instance.StudyTime),
-        },
-      ],
-    },
-    cornerstoneOverlayBottomLeft: {
-      id: 'cornerstoneOverlayBottomLeft',
-
-      items: [
-        {
-          id: 'SeriesNumber',
-          customizationType: 'ohif.overlayItem',
-          label: 'Ser:',
-          title: 'Series Number',
-          condition: ({ instance }) => instance && instance.SeriesNumber,
-          contentF: ({ instance }) => instance.SeriesNumber,
-        },
-        {
-          id: 'SliceLocation',
-          customizationType: 'ohif.overlayItem',
-          label: 'Loc:',
-          title: 'Slice Location',
-          condition: ({ instance }) => instance && instance.SliceLocation,
-          contentF: ({ instance, formatters: { formatNumberPrecision } }) =>
-            formatNumberPrecision(instance.SliceLocation, 2) + ' mm',
-        },
-        {
-          id: 'SliceThickness',
-          customizationType: 'ohif.overlayItem',
-          label: 'Thick:',
-          title: 'Slice Thickness',
-          condition: ({ instance }) => instance && instance.SliceThickness,
-          contentF: ({ instance, formatters: { formatNumberPrecision } }) =>
-            formatNumberPrecision(instance.SliceThickness, 2) + ' mm',
-        },
-      ],
-    },
-  },
-
-  // ...
-}
+...
 ```
 
 <img src="../../../assets/img/customizable-overlay.png" />