1. If you have multiple ASINs for a single UPC or EAN, consider using the "Listing Loader Template."
2. Sometimes, when you click on "Add a Product" from the "Catalog" menu in Seller Central and enter a UPC or EAN, you may see more than one ASIN. In that case, review all ASIN product pages and select the one with the best content, rankings, and reviews.

3. Once you decide which ASIN to use, return to Catalog and click "Add Products via Upload."

4. Then, under "Download Spreadsheet," click "Get Listing Loader" to the right of "Product Matching only."

5. On the Pop-Up Window, choose the exact template by Marketplace of "Listing Loader Template" to download it.

6. In the Listing Loader Template, make sure to hit 'Enable Editing' first.

7. Insert the ASIN you want to use in the "ASIN Hint" field.

Note:
- If you're using Brand Registry, use the UPC or EAN as the Product ID instead of the ASIN. You can map the ASIN to the UPC or EAN using the Listing Loader.
- If you're using the Listing Loader for a product with only one ASIN on Amazon, don't put the ASIN in the "ASIN Hint" field.
- Unlike the regular flat file, the Listing Loader has some fields not available in the Inventory Loader Template.
8. Once you complete the file, save and upload it to Seller Central using the "Add Products via Upload" option from the "Catalog" menu. Choose your file type, select your file, and upload it. You can skip the "Check File" step if you prefer.

9. Check the processing report to ensure there are no errors. Your products will be to your catalog.