You can, but there is one thing to watch out for...
If you borrow points to rent to someone and THEY cancel you cannot put the points back. You have to use them this year. So be very sure you trust that the person you rent to realizes you may be holding the bag if they back out. We had relatives last year that wanted to go to WDW. As a favor we rented them points because it made the trip considerably cheaper. We had to borrow points because they needed a 2 bedroom for their large group for a week. When they changed their mind, I spent considerable time re-planning, rearranging, transferring and last minute renting (at $8/point, mind you) in order not to be a complete loss.
I told DH no more borrowing for other people unless they realize that I will hunt them down and hurt them if they back out.