@Deirdre2
But if you agree to a reservation change it is not regarded a cancellation and they will be refunded accordingly. It is as simple as that. You can also issue the change from your end - there are no penalties involved as this is NOT a cancellation.
You go to "my reservations", find the relevant one, choose change or cancel, choose change, then enter the new dates. A message will be sent to the guest for them to accept. Once accepted, the unused days will be unblocked in your calendar.