Good question. Probably the best solution would be for you to sign a use and occupancy agreement with your son and daughter-in-law, giving you the right to live in the house for as long as one or both of them owns it. The agreement could also spell out any obligations you may or may not have to pay rent or any expenses, such as utilities. This, however, would not protect you if your son and daughter-in-law were to sell the house. To make sure you got the gifted money back if they were to do so, you could also have them sign a promissory note and mortgage. The promissory note could say that their obligation to pay you back ends at your death.