Solution Guide - Shared Basket

* partner has different white-label fulfillers for those things, e.g. Spreadshirt for the t-shirts
* partner provides a shared basket solution, where he allows customer to buy all those different things via one shared basket and one payment at the partners checkout
* after successful checkout, partner sends white-label fulfillment orders to fulfillment partners, e.g. Spreadshirt for the t-shirts
* Spreadshirt produces t-shirt and sends it to customer (or to partner who sends it to customer)