As a C++ programmer, I note that some methods work this way, namely destructors and assignment.
in reply to RFC: Class::DispatchToAll
I agree with the comment that the "normal" use of supplying your own definition is to override the behavior, not co-operate with multiple versions.
However, I think it would be useful to have an "every parent" dispatch. Each class's implementation works for that (final put-together) class. When you're putting together a new one, you are responsible for coordinating the activity of your direct parent classes; they in turn deal with their parents and members.
Having an every-parent displatch would take the place of "super" which doesn't make much sence in a multiple-inheritence environment.