We've been using Amazon barcodes for a while and now we want to switch to our own barcodes to streamline operations. The product was always listed with its official EAN code - GS1 code.

We've got several sizes listed, each size is a child with its own EAN. We don't want to loose any reviews or sales rank during this procedure. What's the best way to do it?

Create another variant of this product, exactly the same as the old one - I don't think I can do it.

Support was useless and basically said "yes, you need to create a new listing and loose all your reviews etc.". Is it the only way?