Remember that all laws in this area that deal with a husband and wife pertain dependent on any will or document that the spouses have set up and the laws of inheritance in your state, etc. It is very unlikely that they can legally sign away your property.
But I can see WT Legal following up on any documents signing over property, etc., to the WTS to make sure it is solid legally.
As to parents signing away their property, etc., the rights of children are not too strong anyway since they can do what they will with their belongings unless they inherited under a document with restrictions.
Most legal advisors have their clients send a copy of the bequest document to the WTS.
As to elders putting pressure on jws...I have not seen that. Actually, I have seen them try to stay as far away as they can. I can believe there are some individuals. But a concentrated campaign by the WTS...I don't see the proof. yet.