Agreeing with the other posters - we've done this two previous years.
We get two (connecting) rooms for our size family, and have brought an adult nanny/helper/friend along one year.
BUT we're just one group - I mean DH and I are not about to split up ourselves and the kids for a dining reservation! We just say "party of 7" when we make our reservation - they don't know or care how many rooms you have.
THEN (if you are on the Dining Plan) you can just give them your two room keys when it's time to pay and tell them which meals to charge to which rooms (ie. : please put 3 adult meals on this one, and 2 adults/2kids on *that* one).
No problems!