Can change group membership levels

lib/ui/dialogs/multi_choices_dialog.dart

@@ -19,6 +19,8 @@ class MultiChoiceEntry<T> {
     this.subtitle,
   })  : assert(id != null),
         assert(title != null);
+
+  bool get hasSubtitle => subtitle != null;
 }
 
 /// Show multiple choices dialog
@@ -81,7 +83,7 @@ class __MultiChoicesEntryDialogState<T>
                       onChanged: (v) => setState(() => _currChoice = v),
                     ),
                     title: Text(f.title),
-                    subtitle: Text(f.subtitle),
+                    subtitle: f.hasSubtitle ? Text(f.subtitle) : null,
                   ))
               .toList(),
         ),