diff --git a/lib/screens/menu_browse_screen.dart b/lib/screens/menu_browse_screen.dart
index 531d9cf..2d2e9df 100644
--- a/lib/screens/menu_browse_screen.dart
+++ b/lib/screens/menu_browse_screen.dart
@@ -1058,9 +1058,16 @@ class _ItemCustomizationSheetState extends State<_ItemCustomizationSheet> {
 
   Widget _buildSelectionWidget(MenuItem item, MenuItem parent) {
     final isSelected = _selectedItemIds.contains(item.itemId);
+    final siblings = widget.itemsByParent[parent.itemId] ?? [];
 
-    // Radio button if max selection is 1
-    if (parent.maxNumSelectionReq == 1) {
+    // Determine if this should behave as a radio button group:
+    // 1. Explicit: maxNumSelectionReq == 1
+    // 2. Inferred: Group has exactly one default-checked item (implies single selection)
+    final isRadioGroup = parent.maxNumSelectionReq == 1 ||
+        (siblings.where((s) => s.isCheckedByDefault).length == 1 &&
+         siblings.every((s) => !s.requiresChildSelection));
+
+    if (isRadioGroup) {
       return Radio<int>(
         value: item.itemId,
         groupValue: _getSelectedInGroup(parent.itemId),
@@ -1090,10 +1097,17 @@ class _ItemCustomizationSheetState extends State<_ItemCustomizationSheet> {
       _validationError = null;
 
       final isCurrentlySelected = _selectedItemIds.contains(item.itemId);
+      final siblings = widget.itemsByParent[parent.itemId] ?? [];
 
-      // For radio buttons (max = 1), deselect siblings and always select the clicked item
-      if (parent.maxNumSelectionReq == 1) {
-        final siblings = widget.itemsByParent[parent.itemId] ?? [];
+      // Determine if this should behave as a radio button group:
+      // 1. Explicit: maxNumSelectionReq == 1
+      // 2. Inferred: Group has exactly one default-checked item (implies single selection)
+      final isRadioGroup = parent.maxNumSelectionReq == 1 ||
+          (siblings.where((s) => s.isCheckedByDefault).length == 1 &&
+           siblings.every((s) => !s.requiresChildSelection));
+
+      // For radio buttons, deselect siblings and always select the clicked item
+      if (isRadioGroup) {
         for (final sibling in siblings) {
           _selectedItemIds.remove(sibling.itemId);
           _deselectDescendants(sibling.itemId);