Legal Question in Wills and Trusts in Pennsylvania

Re: Can mother-in-law give her half of house to son?

Since you said in your question that your wife is "on the mortgage with her mother", I assume that your wife's name is also on the legal title to the home. If your mother-in-law deeded an interest in the house to your wife, if the deed says that their (wife and her mother) interest is as "joint tenants with right of survivorship", then your wife will have sole title upon the death of her mother. There would be no interest left in your mother-in-law to transfer by her will.

If no deed transfer was made to put your wife in title, or if she is in title with her mother only as tenants in common, then her mother could leave an interest to others by her will.

Another alternative would be if there was a written co-owner agreement between your wife and her mother when you and your wife moved in to help her with the house payments. If such an agreement was also contained in a memorandum that was recorded in the office of the Recorder of Deeds for the County where the house is located, it may govern disposition of the house.