@Kathy842 I would make it very clear to guests when they book that no one who is not accounted for on the reservation will be admitted to the property, and that the booking party has to be among the guests. That showing up with more people will mean their reservation will be cancelled on arrival. You may have this stated on your listing, but it's a good idea to also send the guest that message when they book, so that they can cancel it right away if they have nefarious intentions.
I wouldn't send it on its own, as that might seem somewhat aggressive, but in a message where you give them other info.