When someone replies by default the following will happen.
You will receive an email with the details of the reply.
We will update the subject in in your calendar* adding either [CONFIRMED], [NOT GOING TO MAKE IT/RESCHEDULE], [SMSREPLY]
We will add the full details to the body of the appointment.
You can edit all these options by going to Settings > Edit Calendar > Click edit on the calendar you want to edit.
If you want to edit the text that is inserted into your calendar when someone replies you can go to Settings > Business Settings.