diff --git a/src/Umbraco.Web.UI.Client/src/core/mocks/data/document-type.data.ts b/src/Umbraco.Web.UI.Client/src/core/mocks/data/document-type.data.ts
index ef11f86957..47913c8464 100644
--- a/src/Umbraco.Web.UI.Client/src/core/mocks/data/document-type.data.ts
+++ b/src/Umbraco.Web.UI.Client/src/core/mocks/data/document-type.data.ts
@@ -1009,6 +1009,13 @@ class UmbDocumentTypeData extends UmbEntityData<DocumentTypeModel> {
 		const items = this.treeData.filter((item) => keys.includes(item.key ?? ''));
 		return items.map((item) => createDocumentTypeTreeItem(item));
 	}
+
+	getAllowedTypesOf(key: string): Array<DocumentTypeTreeItemModel> {
+		const documentType = this.getByKey(key);
+		const allowedTypeKeys = documentType?.allowedContentTypes?.map((documentType) => documentType.key) ?? [];
+		const items = this.treeData.filter((item) => allowedTypeKeys.includes(item.key ?? ''));
+		return items.map((item) => createDocumentTypeTreeItem(item));
+	}
 }
 
 export const umbDocumentTypeData = new UmbDocumentTypeData();