Was just describing the same problem. Perhaps an Assignment function where you add the emails and tracks/parts would solve the problem? As I think about it (I'm not a choir director or music teacher), the function would have a number of states or steps.
Unassigned - You create a list of the tracks or parts you need for the recording, noting an instrument or vocal part.
Assigned - That status changes to Assigned when you assign a student or member a part/track. Enter their email, and a note. Hit send. They get a link with a message that you have assigned them a part.
Opened - The status changes to Opened when the student or member opens the assignment in EVC.
Working - Once the student or member records a part/track, the state changes to Working.
Waiting Review - When the student or member is satisfied with the part/track, they click a "Submit" button changing the status to Waiting Review. You get an alert the next time you log into the application.
Director or teacher reviews the part/track. You have two options at this point:
Rerecord - If the submitted part/track has a problem, you flag it as Rerecord and add a note. This sends an email to the student or member with a link asking them to rerecord the track and providing the reason. The status is set back to "Assigned" and the steps repeat from that point forward.
Accepted - When you are satisfied with a track, you click an "Accepted" button triggering a message to the student or member that you have accepted the recording. Perhaps the app might want to include the ability for you to send a note when you click "Accept".
The step names are just suggestions. You might have better ones!