diff --git a/LesionTracker/client/lib/customCommands.js b/LesionTracker/client/lib/customCommands.js
index d9d882298..776d5804c 100644
--- a/LesionTracker/client/lib/customCommands.js
+++ b/LesionTracker/client/lib/customCommands.js
@@ -3,8 +3,14 @@ import { _ } from 'meteor/underscore';
 import { OHIF } from 'meteor/ohif:core';
 
 Meteor.startup(() => {
+    const { toolManager } = OHIF.viewerbase;
+    const contextName = 'viewer';
+
     // Enable the custom tools
     const customTools = [{
+        id: 'bidirectional',
+        name: 'Target'
+    }, {
         id: 'nonTarget',
         name: 'Non-Target'
     }, {
@@ -14,12 +20,25 @@ Meteor.startup(() => {
         id: 'targetUN',
         name: 'UN Target'
     }];
-
     customTools.forEach(tool => {
         _.defaults(OHIF.hotkeys.defaults.viewer, { [tool.id]: '' });
-        OHIF.commands.register('viewer', tool.id, {
+        OHIF.commands.register(contextName, tool.id, {
             name: tool.name,
-            action: () => OHIF.viewerbase.toolManager.setActiveTool(tool.id)
+            action: tool.action || (() => toolManager.setActiveTool(tool.id))
+        });
+    });
+
+    // Enable the custom commands
+    const customCommands = [{
+        id: 'linkStackScroll',
+        name: 'Link',
+        action: OHIF.viewerbase.viewportUtils.linkStackScroll
+    }];
+    customCommands.forEach(command => {
+        _.defaults(OHIF.hotkeys.defaults.viewer, { [command.id]: '' });
+        OHIF.commands.register(contextName, command.id, {
+            name: command.name,
+            action: command.action || (() => toolManager.setActiveTool(command.id))
         });
     });
 });
diff --git a/Packages/ohif-measurements/client/components/association/associationModal/associationModal.js b/Packages/ohif-measurements/client/components/association/associationModal/associationModal.js
index 7148cef0f..1f1a509fd 100644
--- a/Packages/ohif-measurements/client/components/association/associationModal/associationModal.js
+++ b/Packages/ohif-measurements/client/components/association/associationModal/associationModal.js
@@ -117,7 +117,8 @@ Template.dialogStudyAssociation.onCreated(() => {
                     studyInstanceUids: studyInstanceUids,
                     patientId: relatedStudies[0].patientId,
                     earliestDate: studyDates[0],
-                    latestDate: studyDates[studyDates.length - 1]
+                    latestDate: studyDates[studyDates.length - 1],
+                    isLocked: false
                 };
 
                 // Insert this timepoint into the Timepoints Collection
diff --git a/Packages/ohif-measurements/client/lib/jumpToRowItem.js b/Packages/ohif-measurements/client/lib/jumpToRowItem.js
index f44724bc9..462052194 100644
--- a/Packages/ohif-measurements/client/lib/jumpToRowItem.js
+++ b/Packages/ohif-measurements/client/lib/jumpToRowItem.js
@@ -1,4 +1,5 @@
 import { $ } from 'meteor/jquery';
+import { _ } from 'meteor/underscore';
 import { OHIF } from 'meteor/ohif:core';
 import 'meteor/ohif:viewerbase';
 
@@ -63,7 +64,15 @@ function renderIntoViewport(viewportIndex, studyInstanceUid, seriesInstanceUid,
 }
 
 function syncViewports(viewportsIndexes) {
-    OHIF.viewer.stackImagePositionOffsetSynchronizer.activateByViewportIndexes(viewportsIndexes);
+    const synchronizer = OHIF.viewer.stackImagePositionOffsetSynchronizer;
+    const linkableViewports = synchronizer.getLinkableViewports();
+    if (linkableViewports.length) {
+        const linkableViewportsIndexes = _.pluck(linkableViewports, 'index');
+        const indexes = _.intersection(linkableViewportsIndexes, viewportsIndexes);
+        if (indexes.length) {
+            OHIF.viewer.stackImagePositionOffsetSynchronizer.activateByViewportIndexes(indexes);
+        }
+    }
 }
 
 /**
diff --git a/Packages/ohif-viewerbase/client/lib/classes/StackImagePositionOffsetSynchronizer.js b/Packages/ohif-viewerbase/client/lib/classes/StackImagePositionOffsetSynchronizer.js
index 2ae39c574..c5de4a417 100644
--- a/Packages/ohif-viewerbase/client/lib/classes/StackImagePositionOffsetSynchronizer.js
+++ b/Packages/ohif-viewerbase/client/lib/classes/StackImagePositionOffsetSynchronizer.js
@@ -68,7 +68,7 @@ export class StackImagePositionOffsetSynchronizer {
             this.synchronizer.add(viewport.element);
             this.syncedViewports.push(viewport);
             viewportIndexes.push(viewport.index);
-            
+
             $(viewport.element).on(StackImagePositionOffsetSynchronizer.ELEMENT_DISABLED_EVENT, this.elementDisabledHandler(this));
         });
 
@@ -104,7 +104,7 @@ export class StackImagePositionOffsetSynchronizer {
 
         for (let i = 0; i < length; i++) {
             const viewport = this.syncedViewports[i];
-            
+
             if (viewport.element === viewportElement) {
                 return viewport;
             }
@@ -155,25 +155,31 @@ export class StackImagePositionOffsetSynchronizer {
         return viewports;
     }
 
+    isViewportsLinkable(viewportElementA, viewportElementB) {
+        const viewportAImageNormal = this.getViewportImageNormal(viewportElementA);
+        const viewportBImageNormal = this.getViewportImageNormal(viewportElementB);
+
+        if (viewportAImageNormal && viewportBImageNormal) {
+            const angleInRadians = viewportBImageNormal.angleTo(viewportAImageNormal);
+
+            // Pi / 12 radians = 15 degrees
+            // If the angle between two vectors is Pi, it means they are just inverted
+            return angleInRadians < Math.PI / 12 || angleInRadians === Math.PI;
+        }
+
+        return false;
+    }
+
     getLinkableViewports() {
         const activeViewportElement = this.getActiveViewportElement();
-        const activeViewportImageNormal = this.getViewportImageNormal(activeViewportElement);
         const viewports = [];
 
         $('.imageViewerViewport').each((index, viewportElement) => {
-            const viewportImageNormal = this.getViewportImageNormal(viewportElement);
-
-            if (activeViewportImageNormal && viewportImageNormal) {
-                const angleInRadians = viewportImageNormal.angleTo(activeViewportImageNormal);
-
-                // Pi / 12 radians = 15 degrees
-                // If the angle between two vectors is Pi, it means they are just inverted
-                if (angleInRadians < Math.PI / 12 || angleInRadians === Math.PI) {
-                    viewports.push({
-                        index: index,
-                        element: viewportElement
-                    });
-                }
+            if (this.isViewportsLinkable(activeViewportElement, viewportElement)) {
+                viewports.push({
+                    index: index,
+                    element: viewportElement
+                });
             }
         });