[Zope] Question about inheriting Z Classes

Hello! I have created my own document type (Z Class) in Zope (let's call it "My document") and I'd like to implement other document's features into it (concretely, it is workflow feature from Metaflow document, but it can be anything else). I tried to do it the way I know - to create new Z Class and inherit the existing objects as Base classes into this Z Class. But I don't see this "Metaflow document" in the list between these classes (although Metaflow is properly installed and used in the Zope), so there is not possibility to inherit it as base class. Is there some possibility how to use behavior of this class in my classes or how to inherit the class other way? Thank to all for the answer! Lubos.