Quoted from Coindork:Simple solution to selling a jointly owned property.
One party puts a value on it and asks the other party if they are a buyer or a seller.
Quoted from JohnTTwo:Exactly!!! So simple
How is it simple when the OP already stated the other party doesn't want to settle. Doesn't sound like the son-in-law has any interest in working something out with his aunt.
Quoted from HandsOfStone:I don't think he wants to settle for half of the value. He wants to wait it out and get the whole house (if he outlives her, he's 72 himself).
Quoted from HandsOfStone:The house deed states "Right of Survivorship". No one can sell or transfer their part. It's last man standing. He had his lawyer buddy draw it up that way back in 2004. She had no idea. He had only been married to her daughter for a few years and hadn't shown his true colors yet.