If an order is processing or completed, it is usually no longer possible to add coupons or added a new referrer to that coupon.
However, in the “Coupon Affiliates” meta box shown when editing individual orders, you will see a “Add a tracking coupon to this order” link.
This lets you attach an affiliate coupon to an order purely for tracking purposes, therefore it will start tracking statistics on that affiliate coupons dashboard.
Since the order is completed:
- It will NOT apply any discounts to the order.
- It will also NOT grant any unpaid commission to that coupon if the order is already completed. You would need to apply this manually.
