We are adding IAP feature to our phone and tablet app now which will give our users the ability to subscribe to our service via mobile devices. For our current version, we will offer two different type of subscriptions, such as 'Limited' and 'Deluxe'. So basically, a registered user will be able to subscribe to a 'limited' or 'deluxe' package; moreover, he will be able to upgrade or downgrade his subscription, for instance from limited to deluxe package or vice versa. We have implemented it on our Android version and basically Google IAB v3.0 supports the subscription upgrade/downgrade feature. Since we also have Amazon version of our app, we want to implement the same feature too. I went over the IAP v2.0 reference and documentation, however, I couldn't find any information related to subscription upgrade and downgrade feature. Does Amazon IAP v2.0 supports subscription upgrade/downgrade feature? Thank you.