This would be a useful feature to have, especially since the shipping integrations in Linnworks don't give many options for shipping add-ons. For example; if we want to add "signature required" to a shipment but have already "processed" the order in Linnworks.  This option is not available with the current Easyship/Linnworks integration that we are using so we have had to do it after the fact. Or they may have been a mistake with the shipping option originally selected for the order.  Marketplaces allow us to change tracking numbers after the fact but this would be useful because we track all of our shipments through Linnworks.