Some customer may get confused with the sourcing list and import list and wonder how they work.
Sourcing list only show the product that you source from Topdser. Once you submit a sourcing request or ask for quote, it will add to the sourcing list automatically. You can add it in import list after product is sourced.
Import list means the products that are ready to upload to Shopify. If you import the products from AliExpress, it will go straightly to import list.
If you add the product from both AliExpress and Topdser sourcing list , it will display supplier as Aliexpress and 1688.