Ability to track commission payouts at stock design or decorated product level not just store

Very useful feature for selling stock designs supplied by external collaborators paid on a per-use basis or royalty. Current system only tracks commissions at store level which is not ideal for tracking commissions if customers want a centralized shopping cart under one store. Solution is to set commission at design or decorated product level that will be paid out to the collaborators - illustrators/graphics artists, etc.