Good Afternoon @Seller_pFIKsnBIZkxjW,

Have you tried using the Variation Wizard to update the existing variation family?

1. Select the option Add to or update an existing variation family and search for the ASIN for the parent-child listing in a variation family. The parent listing appears with Parent under the "parentage" column. If there are existing child variations, they appear with Child under the "parentage" column.
2. For any existing child variations that you created, use Edit to edit information.
3. If you searched for an ASIN created by another seller, click Sell Yours, if the child variation you want to add is already listed under the parent SKU. Provide the Quantity, Price and Condition to add your offer.
4. Click Add to add a new child variation to the variation family, and use the editable columns to provide required information, and then click Save.
5. Repeat step 4 to add more child variations.
6. You can use Edit or Delete to edit or delete the newly added variation.
7. Click Generate Template to get a pre-filled inventory file template, which you can modify to add the new variations.
8. Once you have completed modifications to the inventory file, go to Catalog, Add Products via Upload, select Upload your spreadsheet, browse and select your file, and click Submit products.

Note: In the Excel template, delete the quantity amounts for any FBA SKUs in your inventory. If you leave the quantities intact, it will convert any FBA inventory to Merchant Fulfilled. Leave the Update/Delete column set to Partial Update.

If you run into any issues editing the variation, please reach out to Selling Partner Support so they can troubleshoot the variation update with you. You may provide the CASE ID you create with them on this discussion so I can monitor the case. Hope you have a great week!

Cheers, Cooper_Amazon