Sadly, we face this issue on a regular basis.
These are my 2 cents on how we handle this thorny issue:
1. anytime a parent 'who is not involved' asks for records, we make them pay for it AND we make a courtesy call to the parent 'who is involved' letting them know about record being released. Making them pay often makes the 'uninvolved' parents not want the records. And letting the other parent know in advance defuses any future blow-ups.
2.For the parent who cannot be at appointments but asks to be briefed every time after the appointment, we do it once and then insist that the child will not be seen unless both parents are present.
3.For the parent who wants to be notified of appointments, we let them know that we are not responsible for "inter-parent" communication. We will call one number for appointment reminders and they have to let the other party know.