All of the above answers have assumed these are linked contracts under a single master contract. While this is usually true even for resale, it is not always so. Sometimes when you buy a resale contract
DVC fails to link them and if they don't do it initially, they won't go back and do it. And if there is any variation at all in the ownership, they cannot be linked. Separate contracts of a single owner are treated like different people in most cases though in the past DVC has shown some flexibility on a case by case basis. You'd lose the aggregate booking windows.
So if by chance these were not linked, the answers vary slightly. You would book some rooms with one contract and some with another and then link them. The reservation would act as one in that situation. The problem areas with separate contracts are where you need the points in one contract such as that last night were you don't have enough points in one, or have banked or borrowed points you need to use up. The other area where points must be in one contract is for exchange options like II and esp
DCL. In the past DVC has been flexible where obviously appropriate even transferring banked or borrowed points and allowing multiple exchanges in a use year when the rule at the time was one per use year.