Almost every product that I sell has to be shipped in multiple boxes—they're large kits. In WooCommerce I have items created as product bundles, which contain an individual item for each shipping box (e.g. If you buy one kit, behind the scenes you're actually purchasing a bundle of 2-4 different items, one for each shipping box). When I bring these orders into ShippingEasy each box shows up as a separate item in the order. I then split the order, and once they're split I have Shipping Rules that automatically input Saved Selections for all of the individual boxes.

The downside to this is that a single order becomes 2-4 orders, which all still keep the same order number in ShippingEasy, but then my customers receive a shipping confirmation email for every single item in the order, instead of one email for the entire order.

The system could either recognize that multiple orders share a single order number and automatically send only one email for all of them or, alternatively, you could provide a way to select multiple items in your Shipment History and then manually send a single email that contains all the relevant tracking numbers associated with the selected shipments.