Your agent can add multiple people to a listing so that members of a family or co-owners can share in the process. Each one can be set to just be notified of appointments or can confirm them. Because schedules vary from person to person, having someone else to confirm an appointment can help make sure that notifications are not missed. 

ShowingTime sends push notifications and/or an text to each person that is configured on a listing at the same time. Anyone who receives the notification can either confirm or deny the appointment. If you have talked with your agent and one or more people only need to be notified, settings can be changed.