Natalie:
Disney tries to accommodate a request like connecting rooms, but can't guarantee it, so if it might be a deal-breaker for you, I'd consider the
All-Star Music Suites.
Priced just $25 or so extra a day over two rooms, the suites have the same square-footage as two connecting rooms. They provide two bathrooms, but also a kitchenette: perfect for breakfast, refrigerating drinks or warming up a late-night snack for the girls. What they also provide is a gathering spot for everyone to congregate in the living room, rather than on the beds in the connecting rooms.
The only exception to the suite are the chair and ottoman that make out into comfortable cots, similar to rollaways, and the sleeper sofa. If any of the girls are like the Princess and the Pea, the bed arrangement may not be worth having the living area...
Wishing y'all a magical vacation!
Whitney