To customize the settings for guest on reservations, we'll go to Settings > Reservations > Reservation Types
Once here, we'll go select a specific reservation and EDIT:
Now we'll just scroll down until we see the 'guests' settings:
If you check the box to 'Allow Guests on Member Portal,' you can create the Guest Fee
Once this is saved, when a member goes to create a reservation, they will have the option to bring a guest and input their information.