diff --git a/hierarchical_select.module b/hierarchical_select.module
--- a/hierarchical_select.module
+++ b/hierarchical_select.module
@@ -399,6 +399,18 @@
  * Hierarchical select form element type #process callback.
  */
 function hierarchical_select_process($element, $edit, &$form_state, $form) {
+  // If we're in a callback where the ids have already been assigned to
+  // the elements, but we don't have information about them yet, then
+  // do nothing and return the element has is.
+  if (isset($_POST['hs_form_build_id']) && !isset($edit['hsid'])) {
+    return $element;
+  }
+  // If an id has been assigned and we can get to it, then use it and
+  // flag the whole process has a rebuild.
+  if (is_array($edit) && isset($edit['hsid'])) {
+    $element['#value']['hsid'] = $edit['hsid'];
+    $rebuild = TRUE;
+  }
   if (!is_array($element['#value']) || !isset($element['#value']['hsid'])) {
     // The HSID is stored in the session, to allow for multiple Hierarchical
     // Select form items on the same page of which at least one is added through
@@ -462,6 +474,13 @@
        ),
      )
   );
+  // If rebuiliding the form due to external AHAH events, such as
+  // CCK "Add more values" form rebuilding, then everything's already in place
+  // on the JS side (that's an AHAH submission after all), so, flag the widget
+  // as so.
+  if ($rebuild) {
+    $settings['HierarchicalSelect']['settings'][$hsid]['updatesEnabled'] = TRUE;
+  }
   _hierarchical_select_add_js_settings($settings, $form_state);
 
   // Basic config validation and diagnostics.