Hi prestonpoulter,
Thanks for contributing to our forum. We do not currently offer a feature which would allow you to tell which of your Inventory items have active eBay listings associated with them from your Manage Inventory page so, if you are unsure whether a certain product is currently listed on eBay, you would need to search for the item on your Active Listings page to confirm.
Although it is also not possible to associate a listing which is already active on eBay with an Inventory item, you can link any of your existing saved listings to the appropriate Inventory items by opening them up, checking the box next to “Is this an inventory item?” below the description editor, selecting the desired Inventory item and then saving your changes.
Updating an existing saved listing in this manner would cause any future listings you post from that saved listing to be associated with the selected Inventory Item, but would not have any impact on active listings you may have already posted from the saved listing.
I hope this helps. If you need any further assistance with your account, please feel free to contact our Customer Support team by mousing over the “Help” tab within on our site and selecting the “File Support Case” option.
-Mike