diff --git a/Source/WebCore/accessibility/AccessibilityObject.h b/Source/WebCore/accessibility/AccessibilityObject.h
index 8a1ebea..831242b 100644
--- a/Source/WebCore/accessibility/AccessibilityObject.h
+++ b/Source/WebCore/accessibility/AccessibilityObject.h
@@ -497,6 +497,7 @@
     void decrement() override { }
 
     virtual void updateRole() { }
+    bool childrenInitialized() const { return m_childrenInitialized; }
     const AccessibilityChildrenVector& children(bool updateChildrenIfNeeded = true) override;
     virtual void addChildren() { }
     enum class DescendIfIgnored : uint8_t { No, Yes };
@@ -827,7 +828,6 @@
 #endif
     
 protected: // FIXME: Make the data members private.
-    bool childrenInitialized() const { return m_childrenInitialized; }
     AccessibilityChildrenVector m_children;
     mutable bool m_childrenInitialized { false };
     AccessibilityRole m_role { AccessibilityRole::Unknown };
diff --git a/Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.cpp b/Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.cpp
index 27fd89f..b26e162 100644
--- a/Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.cpp
+++ b/Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.cpp
@@ -209,20 +209,20 @@
     queueRemovalsAndUnresolvedChanges({ });
 }
 
+static bool shouldCreateNodeChange(AXCoreObject& axObject)
+{
+    // We should never create an isolated object from an ignored object or one with an invalid ID.
+    return !axObject.accessibilityIsIgnored() && axObject.objectID().isValid();
+}
+
 std::optional<AXIsolatedTree::NodeChange> AXIsolatedTree::nodeChangeForObject(Ref<AXCoreObject> axObject, AttachWrapper attachWrapper)
 {
     ASSERT(isMainThread());
+    ASSERT(axObject->objectID().isValid());
 
-    // We should never create an isolated object from an ignored object.
-    if (axObject->accessibilityIsIgnored())
+    if (!shouldCreateNodeChange(axObject.get()))
         return std::nullopt;
 
-    if (!axObject->objectID().isValid()) {
-        // Either the axObject has an invalid ID or something else went terribly wrong. Don't bother doing anything else.
-        ASSERT_NOT_REACHED();
-        return std::nullopt;
-    }
-
     auto object = AXIsolatedObject::create(axObject, this);
     NodeChange nodeChange { object, nullptr };
 
@@ -458,7 +458,7 @@
         updateNodeProperty(*treeAncestor, AXPropertyName::ARIATreeRows);
 }
 
-void AXIsolatedTree::updateChildren(AXCoreObject& axObject)
+void AXIsolatedTree::updateChildren(AXCoreObject& axObject, ResolveNodeChanges resolveNodeChanges)
 {
     AXTRACE("AXIsolatedTree::updateChildren"_s);
     AXLOG("For AXObject:");
@@ -489,12 +489,34 @@
         return;
     }
 
-#ifndef NDEBUG
     if (axAncestor != &axObject) {
         AXLOG(makeString("Original object with ID ", axObject.objectID().loggingString(), " wasn't in the isolated tree, so instead updating the closest in-isolated-tree ancestor:"));
         AXLOG(axAncestor);
+        for (auto& child : axObject.children()) {
+            auto* liveChild = dynamicDowncast<AccessibilityObject>(child.get());
+            if (!liveChild || liveChild->childrenInitialized())
+                continue;
+
+            if (!m_nodeMap.contains(liveChild->objectID())) {
+                if (!shouldCreateNodeChange(*liveChild))
+                    continue;
+
+                // This child should be added to the isolated tree but hasn't been yet.
+                // Add it to the nodemap so the recursive call to updateChildren below properly builds the subtree for this object.
+                auto* parent = liveChild->parentObjectUnignored();
+                m_nodeMap.set(liveChild->objectID(), ParentChildrenIDs { parent ? parent->objectID() : AXID(), liveChild->childrenIDs() });
+                m_unresolvedPendingAppends.set(liveChild->objectID(), AttachWrapper::OnMainThread);
+            }
+
+            AXLOG(makeString(
+                "Child ID ", liveChild->objectID().loggingString(), " of original object ID ", axObject.objectID().loggingString(), " was found in the isolated tree with uninitialized live children. Updating its isolated children."
+            ));
+            // Don't immediately resolve node changes in these recursive calls to updateChildren. This avoids duplicate node change creation in this scenario:
+            //   1. Some subtree is updated in the below call to updateChildren.
+            //   2. Later in this function, when updating axAncestor, we update some higher subtree that includes the updated subtree from step 1.
+            updateChildren(*liveChild, ResolveNodeChanges::No);
+        }
     }
-#endif
 
     auto oldIDs = m_nodeMap.get(axAncestor->objectID());
     auto& oldChildrenIDs = oldIDs.childrenIDs;
@@ -528,7 +550,11 @@
         if (axID.isValid())
             removeSubtreeFromNodeMap(axID, axAncestor);
     }
-    queueRemovalsAndUnresolvedChanges(oldChildrenIDs);
+
+    if (resolveNodeChanges == ResolveNodeChanges::Yes)
+        queueRemovalsAndUnresolvedChanges(oldChildrenIDs);
+    else
+        queueRemovals(oldChildrenIDs);
 
     // Also queue updates to the target node itself and any properties that depend on children().
     updateNodeAndDependentProperties(*axAncestor);
diff --git a/Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.h b/Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.h
index b1a594c..0317b2e 100644
--- a/Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.h
+++ b/Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.h
@@ -346,7 +346,8 @@
 
     void generateSubtree(AXCoreObject&);
     void updateNode(AXCoreObject&);
-    void updateChildren(AXCoreObject&);
+    enum class ResolveNodeChanges : bool { No, Yes };
+    void updateChildren(AXCoreObject&, ResolveNodeChanges = ResolveNodeChanges::Yes);
     void updateNodeProperty(AXCoreObject&, AXPropertyName);
     void updateNodeAndDependentProperties(AXCoreObject&);