Cancel seats and duplicate seatbookings

1/ Up till now we haven't got the need for the visitors to book a seat, so it had been free seating. But now, with the Corona situation, there is a need to provide assigned seating with safety-space in between.
So we need a possibillity to cancel/enable seats as admin.
2/ We have 3 tickettypes and with the current version of RSEvents!PRO a subscriber can book all three tickettypes at the same seat. We need a "radio"-like funktion that if one books seat 1 in one tickettype it's not available in the other tickettypes. The request also applies at request 1.