Say there are two groups. Suppose group A is having one product which enables user to purchase entire content of the app. It costs 14$. My app has list of Models' profiles user can buy and see. Buying group A, user can view all model's content in app. What about users who do not want to purchase entire app but to purchase some individual model's content? Prices for all models are same: 3$. How do I manage individual model purchasing? They all cannot be in the same group as Apple allows only one in-app products to run at a time in same group.
So I created same type of product in separate number of groups. They rejected my app saying that the products should be in the same group. There will be only one in-app product needs to be created for purchasing entire content. But how about individual artist content product?