diff --git a/app/db/src/app/services/app-state-actions.ts b/app/db/src/app/services/app-state-actions.ts
index 4a7bc4d3..4b35274f 100644
--- a/app/db/src/app/services/app-state-actions.ts
+++ b/app/db/src/app/services/app-state-actions.ts
@@ -7,48 +7,48 @@ import { CardItem } from '../models/card-state';
 import { Overlap } from '../common/bible-reference';
 
 export class AppActionFactory {
-  static newGetSavedPage(pageId: string) {
+  static newGetSavedPage(pageId: string): AppAction {
     return {
       type: 'GET_SAVED_PAGE',
       pageId,
     } as AppAction;
   }
 
-  static newSavePage(title: string) {
+  static newSavePage(title: string): AppAction {
     return {
       type: 'SAVE_PAGE',
       title,
     } as AppAction;
   }
 
-  static newUpdateCurrentPage() {
+  static newUpdateCurrentPage(): AppAction {
     return {
       type: 'UPDATE_CURRENT_PAGE',
     } as AppAction;
   }
 
-  static newUpdateSavedPages(savedPages: IStorable<readonly SavedPage[]>) {
+  static newUpdateSavedPages(savedPages: IStorable<readonly SavedPage[]>): AppAction {
     return {
       type: 'UPDATE_SAVED_PAGES',
       savedPages,
     } as AppAction;
   }
 
-  static newUpdateSavedPage(savedPage: SavedPage) {
+  static newUpdateSavedPage(savedPage: SavedPage): AppAction {
     return {
       type: 'UPDATE_SAVED_PAGE',
       savedPage,
     } as AppAction;
   }
 
-  static newRemoveSavedPage(savedPage: SavedPage) {
+  static newRemoveSavedPage(savedPage: SavedPage): AppAction {
     return {
       type: 'REMOVE_SAVED_PAGE',
       savedPage,
     } as AppAction;
   }
 
-  static newAddCardToSavedPage(card: CardItem, pageId: string) {
+  static newAddCardToSavedPage(card: CardItem, pageId: string): AppAction {
     return {
       type: 'ADD_CARD_TO_SAVED_PAGE',
       card,
@@ -56,7 +56,7 @@ export class AppActionFactory {
     } as AppAction;
   }
 
-  static newAddCard(card: CardItem, nextToItem: CardItem) {
+  static newAddCard(card: CardItem, nextToItem: CardItem): AppAction {
     return {
       type: 'ADD_CARD',
       card,
@@ -64,7 +64,7 @@ export class AppActionFactory {
     } as AppAction;
   }
 
-  static newUpdateCard(newCard: CardItem, oldCard: CardItem) {
+  static newUpdateCard(newCard: CardItem, oldCard: CardItem): AppAction {
     return {
       type: 'UPDATE_CARD',
       newCard,
@@ -72,14 +72,14 @@ export class AppActionFactory {
     } as AppAction;
   }
 
-  static newRemoveCard(card: CardItem) {
+  static newRemoveCard(card: CardItem): AppAction {
     return {
       type: 'REMOVE_CARD',
       card,
     } as AppAction;
   }
 
-  static newMoveCard(card: CardItem, direction: MoveDirection) {
+  static newMoveCard(card: CardItem, direction: MoveDirection): AppAction {
     return {
       type: 'MOVE_CARD',
       card,
@@ -87,48 +87,55 @@ export class AppActionFactory {
     } as AppAction;
   }
 
-  static newUpdateError(error: Error) {
+  static newUpdateError(error: Error): AppAction {
     return {
       type: 'UPDATE_ERROR',
       error,
     } as AppAction;
   }
 
-  static newUpdateCardFontSize(cardFontSize: number) {
+  static newUpdateCardMergeStrategy(strategy: Overlap): AppAction {
+    return {
+      type: 'UPDATE_CARD_MERGE_STRATEGY',
+      cardMergeStrategy: strategy,
+    };
+  }
+
+  static newUpdateCardFontSize(cardFontSize: number): AppAction {
     return {
       type: 'UPDATE_CARD_FONT_SIZE',
       cardFontSize,
     } as AppAction;
   }
 
-  static newUpdateCardFontFamily(cardFontFamily: string) {
+  static newUpdateCardFontFamily(cardFontFamily: string): AppAction {
     return {
       type: 'UPDATE_CARD_FONT_FAMILY',
       cardFontFamily,
     } as AppAction;
   }
 
-  static newUpdateAutocomplete(words: string[]) {
+  static newUpdateAutocomplete(words: string[]): AppAction {
     return {
       type: 'UPDATE_AUTOCOMPLETE',
       words,
     } as AppAction;
   }
 
-  static newUpdateDisplaySettings(settings: IStorable<DisplaySettings>) {
+  static newUpdateDisplaySettings(settings: IStorable<DisplaySettings>): AppAction {
     return {
       type: 'UPDATE_DISPLAY_SETTINGS',
       settings,
     } as AppAction;
   }
-  static newUser(user: User) {
+  static newUser(user: User): AppAction {
     return {
       type: 'SET_USER',
       user,
     } as AppAction;
   }
 
-  static newFindNotes(qry: string, nextToItem: CardItem) {
+  static newFindNotes(qry: string, nextToItem: CardItem): AppAction {
     return {
       type: 'FIND_NOTES',
       qry,
@@ -136,7 +143,7 @@ export class AppActionFactory {
     } as AppAction;
   }
 
-  static newGetNote(noteId: string, nextToItem: CardItem) {
+  static newGetNote(noteId: string, nextToItem: CardItem): AppAction {
     return {
       type: 'GET_NOTE',
       noteId,
@@ -144,21 +151,21 @@ export class AppActionFactory {
     } as AppAction;
   }
 
-  static newUpdateNotes(notes: IStorable<readonly NoteItem[]>) {
+  static newUpdateNotes(notes: IStorable<readonly NoteItem[]>): AppAction {
     return {
       type: 'UPDATE_NOTES',
       notes,
     } as AppAction;
   }
 
-  static newSaveNote(note: NoteItem) {
+  static newSaveNote(note: NoteItem): AppAction {
     return {
       type: 'SAVE_NOTE',
       note,
     } as AppAction;
   }
 
-  static newDeleteNote(note: NoteItem) {
+  static newDeleteNote(note: NoteItem): AppAction {
     return {
       type: 'DELETE_NOTE',
       note,
diff --git a/app/db/src/app/services/app-state-reducer.spec.ts b/app/db/src/app/services/app-state-reducer.spec.ts
index 2eee5178..8e836271 100644
--- a/app/db/src/app/services/app-state-reducer.spec.ts
+++ b/app/db/src/app/services/app-state-reducer.spec.ts
@@ -59,6 +59,14 @@ describe('AppService Reducer', () => {
     TestBed.configureTestingModule({});
   });
 
+  it('UPDATE_CARD_MERGE_STRATEGY', () => {
+    for (const strategy of [Overlap.None, Overlap.Equal, Overlap.Subset, Overlap.Intersect]) {
+      const action = AppActionFactory.newUpdateCardMergeStrategy(strategy);
+      const testState = reducer(preState, action);
+      expect(testState.pageSettings.value.mergeStrategy).toEqual(strategy);
+    }
+  });
+
   it('UPDATE_CARD_FONT_SIZE', () => {
     const action = AppActionFactory.newUpdateCardFontSize(32);
     const testState = reducer(preState, action);