Client "Postpone" ability

I’d love the see the ability for my clients to postpone an appointment instead of simply rescheduling it. Right now I have to select Option-3 (reschedule menu) as an admin, which leaves no way for the client to reschedule.

My client in this situation right now knows their listing won’t be ready on time, but does not yet know when it will be ready. I’d love to see a Postpone option on the clients end that essentially selects Option-3 from their end, then allows them to access the auto-schedule for that order when they’re ready to reschedule. This way no additional coordination is required between me and my client.