extra guests turning up
We have recently had groups bringing extra guests to our property which sleeps 10.
We have a signed contract with the names/ ages etc of each guests, but as we operate a key safe arrival, we do not personally meet the guests, however our housekeeper has reported several times that extra guests have been seeping on sofas and blow up beds at the house which is strictly forbidden under our terms of booking.
We have reminded the guests that extra people are not allowed, and in each case they have either denied it happened saying one of the children wanted to sleep with the others (hence extra bed) or that it was someone who just came for one night. When we have said that this is not permitted, they have said we are unreasonable and said they would write a bad review
Short of putting a web cam in the main hallway area to check numbers, how else can we make sure this does not happen?