If you add a new variation to a listing outside of Sellbrite and wonder why it doesn't exist in your Inventory, that's because Sellbrite doesn't add variations to your Inventory automatically. New Variations need to be linked to Inventory in order for Sellbrite to manage the inventory and product data.
Let's talk about the proper way on how to add a new variation to your listings, and how to make sure the new variation gets linked to your Inventory.
Here are the steps you need to take:
1) You want to make sure that you add the variation to the parent product in your Inventory first. That's because you need to be able to link the variation in your listing to something. Start by going to the "Selling Manager" and finding the parent SKU first.
2) Once you've clicked on the product's, you want to add the new variation to the "Variations" tab on the parent product. Make sure that you're using the same SKU that you used on the listing on the channel. That way you can link the listing variation to the Inventory variation.
3) Now that the variation has been added to the Inventory, all you need to do is run an import from your sales channel, and the variation in the listing will be linked to the Inventory.