Hi Craig.
What central locking system and alarm "fob" system are you using? Want to see if I can get hold of a wiring diagram. To get a better understanding.
It does make sense as usually all central locking systems would open the doors at the same time. But what you need is the "fob" system to have separate outputs for each door. These separate outputs would then control each door.
You can then use the perm for the door switches only. Connected to each of the door solenoids.
Depending on current the solenoids use, run them through relays. I that had a problem on mine where the current was destroying the push buttons. Ended up running them through relays.
I hope I'm making sense.