Oh, my! Be very careful canceling to free up points. Last summer we decided that a reservation that had been booked for a long time needed to be amended at thelast minute by adding an extra night ( military child, last minute travel plan changes.) I called MS and got a very (surprisingly) rude woman who did not much act like she wanted to help me. As I explained to her that we only wanted to add one night on the front end of the trip (and really didn't care where,) she said the only way we could do that was to move to okw from ssr- fewer points. She canceled ssr and went to book okw only to discover the 3rd of the 5 night stay was no longer available (in 30 seconds) and the roomwe hadcanceled at ssr was no longer available for days 1, 2, or 3. All of a sudden, this trip that had been planned for months had rooms for days 1 and 2, days 4 and 5, and nothing for day 3, unless we were willing to pay hundreds of dollars.
I threw a minor hissy fit, talked to at least two supervisors, filed a complaint against the original cm (mine was not the first complaint but apparently the last. ..) and everything was okay. We ended up in three different resorts, but they did find us a room with points. Our dining plan was a nightmare because we had to cancel the one and re book three, and then they ended up being blocked between resorts (that each resort had to individually unblock,) but we had rooms.
Anyhow, don't cancel what you really want just to make changes. Borrow, buy extra points something, but in a busy time, there is no guarantee it will be available 30 seconds after you let it go.