Inherited Composite Class

I am working on a pattern and would like to know if this is a good practice to follow - I have class A as super class and classes B and C are child classes (inherited from class A). I want to build a relationship as "B is a Composite class that can have type of A as a property" (i.e B can have a nested type of A) . Is this a valid relationship I can build ? Is there any issues you see in this relationship