If some of your staff have special qualifications or credentials that allow them to perform add-on services that others can't, you can now control which instructors can be booked performing these services.

To assign instructors to these special add on services, click Appointments > Services > Add-ons > edit the Add-on > click Assign instructors.

Or, you can assign add-on's from an individual instructor's page (click Settings > Instructors > select instructor > Appointment add-ons > Assign specific add-ons).