How To Write A Last Name In Plural . In most cases, you only have to add an s to the end of their entire last name—even if the last letter is y. By convention, names from classical mythology and the bible ending in s show possession with the apostrophe only (“jesus’ teachings”). How To Make Your Last Name Plural from www.english-grammar-revolution.com That device is reserved for creating possessive forms. Do not form a family name plural by using an apostrophe; Examples love, the andersons love, the joneses love, the smiths love, the foxes love, the johnsons love, the kennedys love, the churches love, the days.