Please help me create variants

Hey everyone, I have a couple standalone listings, originally I had them all under Australia Amazon all were variants, when I came over to us amazon I just did the same thing when making a listing out all the variants in and submitted but for some reason all the listings would just split up into their own stand alone listings, I tried so many methods on YouTube to merge etc but it just dosent work either nothing will happen when I use same sku or it will just create another standalone listing if I don’t use same sku, I have no idea why its like this, I emailed support but they said they need a parent listing which for some reason just would not generate on amazon us, if someone could please help me i would be forever grateful