If you are setting up a revenue sharing site (to split profit with a partner) whereby you want to share the profit of the products with the author/creator of the product then you can use the “Revenue Sharing” feature of WP eStore.
Additional Links:
https://www.google.com/#q=split+payment
http://developer.tinypass.com/main/splitpay
https://www.google.com/#q=split+payment+for+affiliates