You could keep all 4 people on the same room reservation and book a room for the other 2 people - it would be booked as a room only and not a package. This way you keep the dining plan for everyone, they can have their own sleeping space. If the tickets are linked to the room package just keep them and then the FP will just have to be booked under that room using those magic bands. So who ever is in the other room will have to have two magic bands one for dining purposes and for FP and a second MB for getting into the room. You can put a name on the MB so you can easily identify which MB is for which purpose. I don't think this is anything illegal or is against any rules, so you should be fine with this plan.
The only thing is the lead name on each reservation has to be different.