By testing my client site, i've found 2 bugs with adding new form :
1/ Obviously my extra field appears on confirmation section on front-end, when admin wants to add new appointment, this extra field doesn't appear on add new form.
2/ With adding new, admin can overlap a new appointment on a "busy" time slot (obviously max slot allocation set is on 1). The dropdown beginning time shows all slots from 0:00 to 23:30, (free, busy or not available)! :grinning:
Thanks in advance for your solution.