Bases and derived class in the context of parameterized classes

This is more of a theory question. I will probably try to code an example once I get some idea.

Assume I have a base class that is not parameterized. Let us call this class B.
If I derive from the base class and add a parameter. Let us call this as class D.

Would class D be considered as derived class of B.
Would the polymorphic rules apply in this case. For example, can I take class B variable and assign to it handle of class D object?

In reply to verif_learner:

I think you are overthinking.

Try some code examples.