I was trying to help person A who was sharing a calendar with multiple people.
Person B accepted the sharing, but then deleted the calendar later on by mistake.

Now when any permissions are changed or set for that calendar by person A, the Person B doesn't receive a new "accept" message, it just tells them their permissions have been changed to the calendar.

How can person B see the calendar again. It isn't in the trash, and the original accept message is gone as well.