How do I call a method of a containing class when adding a dynamic property?

problem:

I have a class C. There exists a method of C that adds dynamic properties that are objects of C.

every time C.add(C1) is called, I want it to trigger a method in C. In addition, I want this to also work for nested properties:

so if an object C has a (dynamic property) C1, which has another dynamic prop called C2, adding C2 to C.C1 should call a method in C.

Another solution to this problem is if I could find parents of dynamic properties -- anyone know how this can be done?