Shipstation does not do a good job of maintaining the customs declarations when orders are merged, split, or edited - I will often be ready to ship an order only to find that the customs declaration is empty, or includes items that are no longer on the order. It takes some effort to create a new declaration, copying in all of the correct values. It would be nice if there were a button that would recreate the declaration based on the items currently in the shipment. Shipstation knows all this information so why not make it easy?
As an aside, I don't like the V3 layout for the customs declaration. In V2 all of the fields were in one row and I could see it directly below the order lineitems. Now the declaration has only one entry per row, making it harder to really see and understand all of the entries, and is hidden off to the side, so it's very difficult to see the lineitems and declaration in the same place for comparison.
