Where add-ons appear in the flow
Add-ons are not a separate booking-flow step. They surface on the reservation confirmation screen at the end of the flow, after the customer has picked a class, instructor and date. Each attached add-on group renders as a section on that page, with its selection rule controlling what the customer can pick.
How customers interact with add-ons
For single-select groups the customer must pick one (or "None" if the group is "Single Optional"). For multi-select groups they tick any combination. The total price updates as add-ons are selected; required selections must be filled in before the confirm button enables.
