How to add new product to Draft subscription using REST API?
I need to use REST API to add new products to existing subscriptions. I've been able to use the Amend action call to successfully do that to an active subscription. However, when I tried to do it to a subscription in draft status, I get an error back that I can't amend an inactive subscription. I can add the new product through the UI, so I know I'm not trying to make a change that Zuora simply won't allow at all.
Is there a REST API call that will let me do this? I haven't tried the Update Subscription call yet. But since the documentation states that it creates a new subscription to replace the old one, just like with the amend call, I suspect that it would also be limited to active subscriptions.