We are staying on a package from Dec 4-11, and a room only 11-12. What is the likelihood we will have to move rooms for that last night? It will be at CBR.
Call reservations and have them note in your first reservation that you are continuing on at that resort. When you check in also mention that. Chances are you will not be made to move then.
More than likely, you won't have to move. Especially since it's just one night at the end. You might have to check out and check back in, though. That just requires you to go down to the front desk to check in that last day.