We’re the points banked before you made the reservation? Where the banked points used to make a different reservation that you cancelled after making a new one?
You select which contract, but the system still pulls banked points from every contract you select before it pulls current year points from the first contract on the list.
They should routinely be used first if they were in the account at the time of the reservation and applicable to the reservation in terms of UY and home resort. If it's in a different UY, at a different home resort or comes into the account later, they won't go back and automatically replace other points.