When a supervisor notification is sent out it is sent out to the supervisor and to every person on the Notification template's recipient list.
With that you can make separate notification templates for each group of users that notifications will be sent out to. Then assign the appropriate template to each supervisor.
I think you can technically use the Auto-insert feature to pull emails addresses from the request record and insert them into the recipient list. However the email addresses would have to be already stored on the request record when it wand there is no way to dynamically add them there either.
Let me know if you have anymore questions about setting this up