This is my understanding of the rules at my airport. We allow pax in on a boarding pass dated for that day. Doesn't matter if my airport is the originating airport, or the destination, or not noted on the BP at all. Some flights will connect or layover in my airport but it is not listed on the BP anywhere. Don't care if they are "used" or not. Some people will fly in, collect their baggage and then come back thru security to eat.