With the new add-ons app, sellers are able to currently offer one-time products as add-ons to their subscription products on their storefront website. This is useful for new customers that are currently buying a subscription product.
I'd be nice if sellers could also offer something similar but to existing customers.
So that sellers could email existing customers asking if they'd like to add an add-on item to their next shipment before the cutoff day (when the shipping list is finalized). The customer could click a link in the email and be taken to a page where they can easily buy and add something to their upcoming shipment.
Since most sellers have more existing customers than they are getting new each month, this would give us a bigger audience to "upsell/cross-sell" to.