Record which revision of a proof was sent to the reviewer.
Keep a dated version receipt beside each proof request.
Your review threads show the revision your teammate shared with a reviewer, even after newer proofs appear.
Track the proof revision each reviewer received in a dated ledger.
Your team gets a dated record of which proof revision went to each reviewer, even as work on the board moves forward.
Track which creative proof revision each reviewer received.
Your reviewers get the proof link, while your review ledger shows which revision you shared with them.