>I'm not sure what you're trying to describe, so it's difficult to provide terminology

Well, there are two situations, where both of them are not supported in .NET.

The first is multipe inheritance, where a sub class can inherit from multiple base classes or, as known in the Wikipedia link, superclasses. This, of course, as mentioned, is not that good.

The second one is about composition. This would then allow a sub class to benefit from components from several base classes. This seems to be related to Polymorphism.