Allow reason for export to be selected per order

After Brexit and IOSS there is a real need to be able to mark a shipment as 'exchange' on the commercial invoice. The customer will have been charged / paid VAT and or duty on the first shipment so when the exchange is sent back out, we need to be able to mark this order as such and link it to the original order as VAT and or duty are not applicable in this instance. Same goes for gits and sample orders. There must be a value on the order and it's associated lines but the reason for export is crucial to driving the VAT / duty aspect.