The "Manage Standing Appointments" menu shows all the Standing Appointment series in one screen and allows for you to Add, Edit or Cancel from this menu. It will only show the current Standing Series and any series of Standing Appointments that ended in the past will not show on this menu.
The "Allow Double Booking Option" when Adding a Standing Appointment will be selected based on the Company Settings. For MedSpa Accounts, if a service has a resource group and secondary resource group - they will auto-fill when creating a standing appointment.
Schedule > Appointments > "Manage Standing Appointments" under Appointment Options or right-click the schedule and select "Manage Standing Appointments"