Disowning Family Members

My wife's sister is the poster child for sociopathic behavior. She's been married, bankrupt, and divorced eight or nine times now, and has recently left her current husband again, I've lost count of how many times she has left and then reconciled.
She cleaned out all of the valuables from MIL's house before the body was cold, meanwhile FIL was in care suffering from alzheimer's.
The night before MIL died, she stole several hundred dollars from MIL's purse, and had been bleeding MIL for years for money.
She had blamed my wife every time she got in trouble when they were children, and continued to do so until MIL died. She threatened to sue my wife when FIL died, claiming that she had been cheated out of a share of her parent's estate, but my wife had documented absolutely everything that had been paid on her behalf and a large chunk was also taken by the bankruptcy trustees. Had my wife not been so meticulous in her records the bankruptcy court could have confiscated her share as well.
My in laws gave SIL tens of thousands of $$ over the years for rent, furniture, food, etc. My wife asked for nothing, and got exactly that. We now live close to 1000 miles away, and have no inclination to visit.