Amazon Color Variation Fix

I have several colour versions of the exact same product sitting in Seller Central under one listing, but the variation relationship is broken—shoppers are not seeing the tidy drop-down selector they expect. I need someone who knows their way around Amazon’s parent-child system (and the flat-file, if that’s quicker) to rebuild the colour variation properly, link each child ASIN to a single parent, and make sure the listing passes Amazon’s checks without losing reviews or search rank. Please confirm you have done colour variations before, outline the simple steps you will take, and deliver either the completed flat-file ready for upload or log into the account (with temporary access) to implement the fix directly. Once finished I will verify that every colour appears in one clean listing, inventory levels remain intact, and no suppressions are triggered.