If you have already integrated your Soldsie store with Shipstation, you can filter on a custom barcode or or numbering system.
1. Go to your Store Settings > General > Advanced Settings or search for "barcode" in the Find field. You will see the section Barcode per Option/Size and click Yes to activate it.
2. Go to a specific product and edit it and you will see the barcode field. You can add numbers or letters to identify the variant. The barcode can be the same or different for multiple variants of the same product.
3. When items are paid you will see Item SKU field for that invoice pulled over into Shipstation.