Hello, I'd like to nest ZClasses in the following way: TestFolderClass --- TestTopicClass --- --- TestItemClass Both FolderClass and TopicClass subclass ObjectManager. The problem is that I'd like to be able to add Item instances both in Topic instances and directly in Folder instances. Also I'd like to nest Topics. The following cases should all be allowed: TestFolder -- TestItem1 -- TestItem2 -- TestTopic1 -- -- TestItem3 -- -- TestItem4 -- -- TestTopic3 -- -- -- TestItem5 -- TestTopic2 etc. - If both TopicClass and ItemClass are defined at the same level (directly in FolderClass), I cannot nest Item in Topic (Item is not available on the Subobjects tab). - If ItemClass is defined in TopicClass then I cannot add Items directly in TestFolders (Item is not available on FolderClass's Subobjects tab). The only solution I can think of is creating an independant ZClass Product called Items. Then it will be available anywhere. But it messes up the Available Objects list. Is there a better solution ? Thanks. Alexandre