This never even occurred to me. Are you saying MS will not let me make ALL of my reservations during one phone call between all of the accounts we have? Why not?
Like someone else said, you have a different 11 month time frame for different contracts. We have a small 50 point Dec UY contract for OKW and our larger 175 Sept UY for OKW. I just reserved seven nights at OKW in early June for next year. I had to creatively transfer some of the points from the Dec 2010 UY contract to the Sep 2010 UY contract to get enough points to get my first six nights (including borrowing from the Sep 2011 UY). I got those six nights seven days ago. Then yesterday, I added the seventh night with my Dec OKW contract - using the rest of the 2010 points and borrowing some from 2011.
I had two small problems. Last Sat when I started the process, I told the CM at MS that I needed to transfer 20 points from my Dec contract to my Sep contract. He misunderstood me and transferred all 50. I would have had points left over in Sep 2010 and not enough in Dec 2010 to make the reservation (because you can't borrow transferred points). So I told him he needed to correct the error. I was on the line waiting for about 10 minutes before he came back and said the error had been corrected. Then he made my six night reservation. He did warn me that I could only do one transfer in or out per UY, though, and was worried that I would have just the few points left over in my Dec 2010 UY.
When I called yesterday for the last night, I gave the reservation number for the first six nights and asked the CM to link the two reservations (two different contracts). BUT, the first CM had made the six night reservation in my husband's name (his is the first name on the contract) and the second had the one additional night in my name (my name is first on that contract).
So she had to change the names around to get them lined up correctly so the two reservations could be linked.
In the end it all worked out. We have our seven nights in a GV at OKW, but for someone less experienced, it might have been a disaster.