I know ShippingEasy offers the ability to import orders via CSV, but ideally, one would be able to also modify specific fields once orders/shipments would already be in the system.
For instance, I like to keep track of the product serial number for each of my shipments. While I could choose to manually modify the individual packing slip each and every time, this would obviously not represent an ideal solution.
Again using the above example, in a perfect world, I would be able to upload a CSV file which would contain, say, the order number and serial number, the latter of which could be inserted into Custom Field 1. Then, upon this file being uploaded, all matching orders/shipments would have themselves updated with this Custom Field 1.