I've done it more than once when I've added on and had banked points in the new contracts. It helped they were all for the same home resort which was also where I had the reservations.
But the interesting thing was the last time, about a year ago, I was on the phone with MS about something else, and I had just passed ROFR so I knew I had new points coming soon. I mentioned to the CM in passing I w/b calling back in a few weeks to do the reallocation once the contract was loaded into the
DVC system.
She went ballistic! Told me she's been an MS CM for 15 years and she's never heard of anyone ever being able to do what I mentioned. Said it was specifically against the rules and any CM who told me she could do it didn't know what she was talking about.
I didn't argue. I didn't ask for details. Heck, I never even asked her anything to get her started in the first place. And I sure didn't tell her I had done this just a few months prior under the same exact conditions.
When the points came in weeks later, I called MS and started explaining the (different!) CM what I wanted to do. Before I could finish explaining it, she had already done it! She interrupted me and said you just want to use the banked points in the new contract to replace as many current UY points as points, right? Done!
It literally took 2 minutes.
Again, as has been pointed out so many times on so many threads on the board, the CM you get makes a big difference.