There is no problem with transmitting a supplementary report and a house bill for the same shipment. And there is no problem with the carrier code for the supplementary being different from the carrier code on the house bill. There are rules that will not allow the same cargo control number (CCN) to be used. So you could not file a supplementary report with the exact same CCN as the house bill. And, there is a rule that requires all of the house bills within a house bill close message to have the same carrier code.