Global cart and only one person who receive payment

Hi !

I'm despertatly searching a solution, because I lose so many time. I want to know if it's possible to enable global cart and configure Marketpress to have only one receiver for money :

I use marketpress on multisite so people can create their stores. A buyer come on my website and chose 1 thing on A store and 2 things on B store. I want that during checkout, all the money go on my account, just my account. (I will pay the store owner later) And I want the global cart too.

So, is it possible ? What kind of payment is possible (paypal, ...) ?

Sincerly,