How is current data effected by adding Attribute mapping in Codisto/Marketplace Connect?

[ReachPhillip]

Our store has a few thousand books on eBay and would like to start using Attribute Mapping through Codisto/Marketplace Connect specifically for the condition category. In the past we have been manually entering each book's condition through the Listings Grid. We don't currently have a field in Shopify that is dedicated to listing. I created a metafield that uses the correct numbers for Codisto/Marketplace but I am worried that if I use the Attribute Mapping to update the condition to the new metafield I will lose/overwrite the condition data that I currently have for all of our books on eBay.

Can anyone let me know if thats for sure the way it works?

If so, is there any other option other than going and updating each book in Shopify to now have the condition through the new metafield?

Thanks!