To make changes to an existing booking, use the "Adjust" button on a booking card. You can add or remove participants, add-ons or coupons as you see fit.
How To Update a Booking
Find the reservation you would like to modify.
Click the "Adjust" button on the associated booking card.
Make changes to attendees/add-ons/coupons.
Select a payment method.
Click "Pay" or "Refund" depending on the adjustments.