Dining plan changes things since everyone on the reservation has to do the plan or not at all. Here's the rub - if you put both daughters names on the 2nd room, your 2nd daughter will not have keys to your room since her key (and the plan) will be tied to room #2 (and if she remains on your room and you do the plan, too, you'll be paying for her twice). If your daughter & family in room #2 are not going to do the plan, then I don't see a problem.
If I were you, I'd leave things as is. When you check in, ask if room #2 is close to you. Maybe someone else has a better solution.
Cyn