post https://rest.cleverbridge.com/subscription/addsubscriptionitem
Adds a new subscription item to an existing subscription or creates a preview of adding a new subscription item to an existing subscription. Optionally, you can overwrite the price of the subscription item that was defined in the Cleverbridge platform. If you want to modify an existing subscription item, use /subscription/updatesubscriptionitem instead.
For XML examples and schemas, see the Additional Examples - Add Subscription Item.