[Zope] Creates classes available to container but NOT add products menu

RegisterClass is cool But what if you don't want to register your product. When you create a product and add a ZobjectManager derived Zclass, all subsequent subclasses appear in the subobject menu but not the Products menu. I have a heap of classes. I do not want every class in the add Products menu. I do want them to be available to the top level container class. How do I do this from within python product code. Chris