The reschedule template you have created and customized can be associated with events in a very simple way. By associating the reschedule template with an event, the emails with the rescheduling notification will reach your users or customers just the way you want.
IMPORTANT: As of October 1, 2023, the "Reschedule" field no longer exists in the event options menu. This customization of events must now be done from the workflows. It is necessary to create workflows to associate the reschedule template with your customers when they reschedule their appointment with you.