I hear what you are saying and you have a valid point. Your son-in-law should not have a problem with putting the house in his wife’s name if you are giving them the money for the downpayment. I hope you had enough seichel to have them sign a prenup as well before the chasanah. If not putting the house in her name is not going to help much if he will withhold a “get” for ransom.
I hope you see my point and where I am going with this,