diff --git a/contributors.yml b/contributors.yml
index 0966b71f78..930896497b 100644
--- a/contributors.yml
+++ b/contributors.yml
@@ -470,6 +470,7 @@
 - yuleicul
 - yuri-poliantsev
 - zeevick10
+- scott-memco
 - zeromask1337
 - zheng-chuang
 - zxTomw
diff --git a/packages/react-router/lib/router/router.ts b/packages/react-router/lib/router/router.ts
index 34c74cc28d..ebf470b87d 100644
--- a/packages/react-router/lib/router/router.ts
+++ b/packages/react-router/lib/router/router.ts
@@ -5378,10 +5378,16 @@ function isSameRoute(
     return true;
   }
 
+  // If only one side has children, they're different routes (e.g., sibling
+  // layouts where one has been patched with children and the other hasn't)
+  if (!newRoute.children?.length || !existingRoute.children?.length) {
+    return false;
+  }
+
   // Otherwise, we look to see if every child in the new route is already
   // represented in the existing route's children
-  return newRoute.children!.every((aChild, i) =>
-    existingRoute.children?.some((bChild) => isSameRoute(aChild, bChild)),
+  return newRoute.children.every((aChild) =>
+    existingRoute.children!.some((bChild) => isSameRoute(aChild, bChild)),
   );
 }