Desired setup: A user subscribes to one of our plans. 1 year later, they must renew their plan. They go to their subscriptions and see the Blue bar that says renew. However, we also have an upgrade option (add-on) for a separate subscription. They should be able to add BOTH to a cart and pay one time.
Is this possible? Right now, when they click the blue Renew button, it creates a basket and doesn't let them add anything to it.