We have a big conference room that can be split into two. We'll call the big conference room CR A, and the two it can split into CR B and CR C.
Each has its own calendar on Outlook. We want to figure out a forwarding system so that if someone books CR A, the booking will also be forwarded to CR B and CR C to prevent double bookings; if someone books CR B, the request will be forwarded to CR A to prevent double bookings. If someone books CR C, the request will be forwarded to CR A to prevent double bookings.