Buy Shipping: Requirements for already confirmed orders

Selling partners are urged to follow best practices and only mark shipments as “Shipped” once (i) shipping is purchased for the shipment; and (ii) the package has been handed off to the carrier for delivery.

Sellers are not allowed to Buy Shipping for orders they have already confirmed, without first canceling the shipments with the CancelShipment option in Seller Central prior to using CreateShipment on Buy Shipping.