Anyone know if I can change the items on a subscription plan in SuiteBilling? Specifically, Month 1 -> Non-Inventory Item#1, Month 2 -> Item#2, etc. There would likely be mixed items starting at different places in the sequence for each customer. We don't currently have SuiteBilling, so I can't test and haven't found this specific use case in the documentation. Thoughts?

Subscription plans are date agnostic. They are just templates. Once a subscription is created, you can add on items and activate them on specific dates. Similarly you will terminate the items that should end before the subscription end date. Since using subscription plans is mandatory (a legacy issue), many clients have subscription plans with only a placeholder item.