It definitely is an edge case. But I'd push back on the 1 subscription per customer idea. Consider any physical fulfillment business, where you have an optiona

It definitely is an edge case. But I'd push back on the 1 subscription per customer idea. Consider any physical fulfillment business, where you have an optional annual membership (amazon prime, costco, whatever) and N subscriptions of varying frequencies for physical products. It doesn't make sense to roll these into a single subscription on the backend (unless the periodicity happens to line up perfectly, and even then there's a heated debate, since you still probably want them to be separate charges). You can go down the route of creating N "virtual" customers for each "real" customer, but it doesn't really solve the problems, because these N customers have a complex relationship with each other that you need to encode and manage. Hence, the name of this post :). It's definitely not easy!