@SueDonJ, you are correct that you can't use the 13 month rule for a SINGLE lock off week. But in my earlier post I was wondering about using part of deeded week A and part of deeded week B (two separate ownerships).
I got onto the Marriott site and looked for the "rules". I couldn't find the detailed rules, so I went into a chat session. I transferred from the automated computer to a real live human. I asked if I could book a partial unit in each of two separate timeshares at the 13 month point. From the delay in answering and a comment from her, I think that she either had to look it up or had to go to a supervisor. Here is what Berenice V wrote:
" Correct, for example you would have to book week DS*9999*22*X and DS*8888*45*B, either full or lock-off placing consecutive or concurrent reservations in the 13 month window."
So, it isn't impossible that the Marriott rep made a mistake, but assuming that she was correct, it looks like if you use two different deeded units that you don't have to reserve the full units but could reserve part of one and part of the other as long as the res's were concurrent or consecutive.
I wonder where I could get a hold of the Marriott fine-print on their rules?