Hi Dragan

>> A subclass can have new properties and methods that its parent class doesn't;

Exactly. But the addition of such methods and properties is a design time issue and requires amendment of the sub class definition.

>> the trouble here is that the addmethod()

I'm sorry, I missed the beginning of this thread, what is AddMethod()? I know of AddProperty() (which is intended to provide a solution to the problem of creating parameter objects at run time without needing to pre-define a class for every possible combination of properties. But that is an entirely different issue).