While it does require a little more recordkeeping, multiple use years and contracts can easily be done. MS will assist with your records- both over the phone and with a printed accounting- which some have found confusing to follow.
We have 4 different contracts, 4 different use years at 2 resorts and, thus far, have had no problems with losing any points. MS has been great about looking up point totals in each account with every phone call.
Enjoy!