diff --git a/src/stores/widgets/WidgetLayoutStore.ts b/src/stores/widgets/WidgetLayoutStore.ts
index 311c7e7c2ab..fa1c5d6dac3 100644
--- a/src/stores/widgets/WidgetLayoutStore.ts
+++ b/src/stores/widgets/WidgetLayoutStore.ts
@@ -104,8 +104,9 @@ export class WidgetLayoutStore extends ReadyWatchingStore {
         }>;
     } = {};
 
-    private pinnedRef: string;
-    private layoutRef: string;
+    private pinnedRef: string | undefined;
+    private layoutRef: string | undefined;
+    private dynamicRef: string | undefined;
 
     private constructor() {
         super(defaultDispatcher);
@@ -133,6 +134,11 @@ export class WidgetLayoutStore extends ReadyWatchingStore {
         this.matrixClient?.on(RoomStateEvent.Events, this.updateRoomFromState);
         this.pinnedRef = SettingsStore.watchSetting("Widgets.pinned", null, this.updateFromSettings);
         this.layoutRef = SettingsStore.watchSetting("Widgets.layout", null, this.updateFromSettings);
+        this.dynamicRef = SettingsStore.watchSetting(
+            "feature_dynamic_room_predecessors",
+            null,
+            this.updateFromSettings,
+        );
         WidgetStore.instance.on(UPDATE_EVENT, this.updateFromWidgetStore);
     }
 
@@ -140,15 +146,17 @@ export class WidgetLayoutStore extends ReadyWatchingStore {
         this.byRoom = {};
 
         this.matrixClient?.off(RoomStateEvent.Events, this.updateRoomFromState);
-        SettingsStore.unwatchSetting(this.pinnedRef);
-        SettingsStore.unwatchSetting(this.layoutRef);
+        if (this.pinnedRef) SettingsStore.unwatchSetting(this.pinnedRef);
+        if (this.layoutRef) SettingsStore.unwatchSetting(this.layoutRef);
+        if (this.dynamicRef) SettingsStore.unwatchSetting(this.dynamicRef);
         WidgetStore.instance.off(UPDATE_EVENT, this.updateFromWidgetStore);
     }
 
     private updateAllRooms = (): void => {
+        const msc3946ProcessDynamicPredecessor = SettingsStore.getValue("feature_dynamic_room_predecessors");
         if (!this.matrixClient) return;
         this.byRoom = {};
-        for (const room of this.matrixClient.getVisibleRooms()) {
+        for (const room of this.matrixClient.getVisibleRooms(msc3946ProcessDynamicPredecessor)) {
             this.recalculateRoom(room);
         }
     };
@@ -168,7 +176,13 @@ export class WidgetLayoutStore extends ReadyWatchingStore {
         if (room) this.recalculateRoom(room);
     };
 
-    private updateFromSettings = (settingName: string, roomId: string /* and other stuff */): void => {
+    private updateFromSettings = (
+        _settingName: string,
+        roomId: string | null,
+        _atLevel: SettingLevel,
+        _newValAtLevel: any,
+        _newVal: any,
+    ): void => {
         if (roomId) {
             const room = this.matrixClient?.getRoom(roomId);
             if (room) this.recalculateRoom(room);
diff --git a/test/stores/WidgetLayoutStore-test.ts b/test/stores/WidgetLayoutStore-test.ts
index 81f373d0f69..ddffe66ae9a 100644
--- a/test/stores/WidgetLayoutStore-test.ts
+++ b/test/stores/WidgetLayoutStore-test.ts
@@ -21,6 +21,7 @@ import WidgetStore, { IApp } from "../../src/stores/WidgetStore";
 import { Container, WidgetLayoutStore } from "../../src/stores/widgets/WidgetLayoutStore";
 import { stubClient } from "../test-utils";
 import defaultDispatcher from "../../src/dispatcher/dispatcher";
+import SettingsStore from "../../src/settings/SettingsStore";
 
 // setup test env values
 const roomId = "!room:server";
@@ -263,4 +264,45 @@ describe("WidgetLayoutStore", () => {
             ]
         `);
     });
+
+    it("Can call onNotReady before onReady has been called", () => {
+        // Just to quieten SonarCloud :-(
+
+        // @ts-ignore bypass private ctor for tests
+        const store = new WidgetLayoutStore();
+        // @ts-ignore calling private method
+        store.onNotReady();
+    });
+
+    describe("when feature_dynamic_room_predecessors is not enabled", () => {
+        beforeAll(() => {
+            jest.spyOn(SettingsStore, "getValue").mockReturnValue(false);
+        });
+
+        it("passes the flag in to getVisibleRooms", async () => {
+            mocked(client.getVisibleRooms).mockRestore();
+            mocked(client.getVisibleRooms).mockReturnValue([]);
+            // @ts-ignore bypass private ctor for tests
+            const store = new WidgetLayoutStore();
+            await store.start();
+            expect(client.getVisibleRooms).toHaveBeenCalledWith(false);
+        });
+    });
+
+    describe("when feature_dynamic_room_predecessors is enabled", () => {
+        beforeAll(() => {
+            jest.spyOn(SettingsStore, "getValue").mockImplementation(
+                (settingName) => settingName === "feature_dynamic_room_predecessors",
+            );
+        });
+
+        it("passes the flag in to getVisibleRooms", async () => {
+            mocked(client.getVisibleRooms).mockRestore();
+            mocked(client.getVisibleRooms).mockReturnValue([]);
+            // @ts-ignore bypass private ctor for tests
+            const store = new WidgetLayoutStore();
+            await store.start();
+            expect(client.getVisibleRooms).toHaveBeenCalledWith(true);
+        });
+    });
 });