Add a user option that when the available date is changed to the late date (for example when a listing is not ready to show due to a delay in repairs ?

Add a user option that when the available date is changed to the late date (for example when a listing is not ready to show due to a delay in repairs being done) , automatically notify anyone who has a scheduled appointment that will occur before this new available date, that they need to reschedule as the property is not ready to show on the date the prospect requested it. (Currently user has to do this manually)