Incidentally, I just read today that Chris Christie has been made the chairman of the transition team. Chris is the one heading it now. My number one theory is that Trump likes to have more eyes and ears in his organization. In this case the son in law is not in a position of power. He is simply on the transition team. It might be a good thing to have if there are any problems. The SIL would know how to get a hold of dad in a hurry.
He also is not directly in the family business ( they have to cover for Donald)...so might have the time??