customize a wordpress theme for marketplace

I bought a complete wordPress theme for a market place ([login to view URL] MarketPlace). The theme is doing pretty everything a marketplace can do. I would like to add a small feature to this theme. The customization is this: I would like my sellers to be able to borough and sell other sellers products. For example. A seller X has a product ABC. I would like another seller Y to be able to add this product ABC from the X's product list to his own list. Once the product ABC is on the list of the seller Y. I would like in case of a client buy this product from Y's list, that 95% of the price goes to the original seller X and the seller Y keeps the 5%. Basically the margin 5% should be configurable by the admin of the market place. The market place theme is actually able to add product from seller to seller but it does not have the feature i described above. And also I want to limit this other sellers addition products to be limited to a maximum of let say 10 products. This maximum number can be configurable by the marketplace admin. Thank you very much for your help in advance.