Can someone explain cancel/rebook?

I started with 4 nights at BWV, 1 night at AKV and 1 night at VGF. I wait listed the AKV night to be replaced with either BWV of VGF. Through stalking/calling I got VGF, no issues and the new VGF night was added to my other VGF night for one reservation.
Today the next night opened at VGF, so I called to add that night and to cancel the BWV night it was replacing.
First the CM warned me that she couldn't hold the VGF night while she canceled the BWV night and that I risked losing both - this was not my experience when I did the same thing a month or so ago - she even said she would put me on hold and check with a manager - can some one confirm that MS cannot hold the villa you want to book, take the points from what you are canceling and apply them to the new booking?
Ultimately she borrowed points to 'hold' the VGF villa, canceled the BWV villa and said she put something through to have the BWV points put back into my 2016 use year which will show up in 72 hours.
I now have a 1 night VGF reservation followed by a 2 night VGF reservation - same size & view - she said she had to give me a seperate reservation - why? Can I call and have them be just one reservation?
Thoughts, advice?

My experience confirms that they can not hold two reservations for you with the same points. If you have enough points to get the reservation before dropping the other, they usually won't mention it, unless the currently held reservation has banked/borrower points that would be released when that one is cancelled.
The other time they usually won't mention this is when there are multiple rooms open in the booking category you are looking for. Since it is very unlikely you won't get what you want.
For the reason that one CM was able to add the second night to your first and the second CM created a separate reservation, I'm not sure. It might have been their familiarity with the system and they might have been worried about getting your nights so they wanted to do it as quickly as possible.
As for those two reservations, you can call MS and have them "link" the reservations in their system so you won't have to change rooms. You will not see any change on your end, but you can double-check when you check-in to make sure you won't have to change rooms.

Thanks - I finally got around to calling MS today and they merged the 1 night with the 2 night reservation so it's now one 3 night reservation.
The helpful CM told me that they typically did those requests first thing in the morning, but it actually happened sooner and was showing on the site as one reservation a couple hours after the phone call.