supply staff to approve or deny scheduled shifts

Staff who work different shifts each week but are on zero hours so cant/dont want to always do what we schedule, once we schedule their shiftsi in for the following week/month- it would be great if they (supply staff only) got a notification to say- can you do these scheduled shifts, and then they are able to accept shift, or deny shift ( a bit like when we request agency staff). then we get notified to say what has been accepted/ denied.