Thank you for posting to the Community! I see that you have also added your support to another similar post and that helps us keep support consolidated to one post. I am going to close this post for comments and direct everyone to this post to show their support: https://help.gocanvas.com/hc/en-us/community/posts/360000480528-Users-have-access-to-all-submissions-not-just-their-own
As for a solution to this issue in the meantime, I recommend using Assignments to assign a incomplete submission to the supervisor to review and edit if necessary. If it stays as an incomplete submission, then anyone can assign, unassign, or claim a submission to complete or edit it. Or, if you want something more structured and that automatically sends the submission to a supervisor, I recommend Workflow using an email field. This can be fully automated so the user in the field doesn't even need to remember the email of the supervisor that they are sending it to.
Post is closed for comments.