Under Reservation Settings > Reservation Types, you can require that a certain number of names are input based on the reservation type. Simply fill out the fields 'Min number of players' and 'Max number of players' and save changes.

This is a great feature to keep track of who is on what court, how many people actually played today, etc. However, if you all are using any kind of Reservation Restrictions (Booking Settings > Restrictions), capturing the names of everyone on a reservation will help the restrictions be more accurate - the system can only enforce restrictions based on the names it has captured for each reservation.

Now for the Reservation Type of Singles, when players are booking from the member portal side, they must have exactly 2 names (min and max of 2) for the reservation to save. If they try to save with only 1 name, it will give them an error that 2 names are required for the reservation type of Singles.