If you wish to add your wife's name to your house property, which is currently in your and your mother's names, the primary method is to execute a registered Gift Deed. Either you, your mother, or both of you can gift a portion of the property to your wife through this deed. Stamp duty will likely be applicable, though some regions offer exemptions for gifts to close relatives. While a will is an option for inheritance, a Gift Deed is the direct way to make her a co-owner during your lifetime.