Approving each guest
For a wedding, a private dinner or anything where the list is the point.
A private occasion waits for your yes by default, and any event can be set to. A guest who claims a place gets a ticket that does not admit anyone yet, and their place is held while you decide — so approving can never fail because the room sold out in the meantime.
They sit under "To approve" on that event's roster, and also under "Needs you" in the sidebar, which is every waiting decision across every event in one list, oldest first. Approve, and their real ticket arrives the same way anyone else's would.
Decline, and the place goes back to the pool and the guest is told — briefly, without a reason, because the reason is yours to give and we will not put words in your mouth. The same message goes to somebody you let go from a waiting list. A person who is not coming should learn it from you rather than from a closed door.
When somebody starts waiting on you, the organizers on your team get one message about that event — at most one an hour, however many people ask.
If somebody turns up unapproved, the door says so in those words rather than refusing them as a fake — those are very different conversations to have at an entrance.