If your friend believes that his father lacks the authority or power to do this, based on what is in the will, then he could potentially get a court order (injunction) preventing his father from selling. (This involves bringing a legal action--lawsuit--to get the order.) He obviously would want to do this *before* the sale occurs, since if the sale goes through and the house is bought by a good faith purchaser who had no knowledge of the irregularity, the courts would not undo or set aside the sale--the house will reamin sold, though in that case, your friend would seem, based on what you write, to have a claim for compensation against his father. Your friend should consult with an attorney right away, bringing a copy of the will and any other documents in his possession in relation to the house, to evaluate this option. The above answer rests on the following assumption: presumably, your friend's grandmother has passed; a will only takes effect on death, and if she is still alive, the will has no power at all. If your friend's father otherwise has the power (such as through a POA) to sell the home, then he could even if the home would go to your friend after his grandmother passes away.