MarketPress - One PayPal Account For All User Generated Stores

I'm creating a site that allows users to create their own store on my network. Instead of having each potential seller enter their own PayPal credentials, by default I would use my own.

The reason for this is combined sales will lower PayPal fees and ease of use for the seller.

Under the network settings of MarketPress, if I enter in my credentials for chained payments, but turn off all gateway options for members will that accomplish this? Or is it possible to set % of sales fee to 100% to do this?

Thanks for the help guys!