If yes, could you guide me? I have a few questions if we upload a flat file in the UK marketplace, will the other EU marketplaces also get updated automatically, or do we need to update them one by one as well?
Normally the listings should sync, so you only need to add the COO to your source marketplace.
Yes, you can upload a Certificate of Analysis (COA) through a flat file by using the compliance attributes section in the relevant category template, usually under “Product Compliance” or “Safety and Compliance” tabs. When you upload it in the UK marketplace, it does not automatically push through to all EU marketplaces unless you are enrolled in Pan-European listings with unified compliance documentation, so in most cases you’ll need to upload the COA separately for each EU marketplace where you want the product active. Sometimes Amazon’s backend links compliance files across marketplaces, but this is inconsistent, so the safest approach is to update each one individually to avoid delays or compliance errors.
You need to put it individually for other markets.