Amazon using own parent-child relation in subscriptions that is different from GooglePlay and AppStore. There a lot of problems with that.
I’m using Amazon App Tester to test IAP, but after purchase there is no child sku, only parent sku is received by event. AFAIK Amazon also doesn’t provide child sku in receipt json and there is no way to get it instead of making request to Amazon API with receipt id, but I dont want to make so.
Somewhere I found that I should add parent sku as product in Unity, but I get “Unavailable product” warnings for all my products and “NoProductsAvailable” initialization error, when adding parent sku as product.