Register a guest for a team

We have events at our club where members are allowed to invite a guest to play as a team in doubles matches. It would be so helpful if there was a way we could put in a guest's name when registering the team without having to add them to the system. The idea is that it would function similarly to adding a guest to a court reservation, where the guest belongs to a specific member (in this case, their teammate who is signing them up for the event), so we have a record of who attended and who was on the courts, without having to make accounts for people who are only going to be using our facility the one time.