If a contract holder is sued, and loses, he might lose his right to the remaining contract payments......which would go to any new contract holder..........but there is no effect on the person buying on contract.

Just like a rental agreement.........a farm can change hands 25 times during the period of the lease agreement, but that does not change the renter's right to rent under the lease.

Banks buy and sell mortgages all the time.......no difference.

See a competent attorney.