If its two contracts under one name, there is no difficulty at all. There can be a problem with booking whole nights from two accounts.
ie: My sister and I are both DVC members, we want to book 5 nights and split the points. The only way to do this is to beek two nights with one account, three nights with the other and transfer half the points required for one night from the account that booked two to the account that booked three.
When both the contracts are under the same name, they just flip the points back and fourth however they need to with no problem at all. I have two contracts, both the same use year, there is no effort made at all to discern witch account is paying for witch nights.