Here is the challenge I have come across.
I work for 3PL fulfillment house. One of our customers sells subscription boxes which can contain multiple different items. The subscription box itself has an SKU assign to it and when an order is pulled from the selling channel, ShipStation obviously doesn't know what the contents of this box is. This creates a problem with custom forms as the contents details can't be populated on the custom form automatically. They can be added on manually but who has time for this!
I think the solution to this is to expand the customs info in the product detail card by enabling addition of more default customs declarations under one SKU. These can then be populated on 1 custom form eliminating the manual aspect...boom...now please ShipStation can you add this on? Pretty please!