how to setup a single payer on a mutisite setup ?

Hi
I need to set up a shop witch will host different seller using multisite
Example
Main Shop
Shop 1
Shop 2
Shop 3

On the main shop i will be able to view all the product from all the shops but once i process the payment i need to send it only to the main shop paypal account.
Is this functionality already build into the script and i'm just unable to find it or i need to hard code it inside the plugin ?
many thanks to how will answer, is few days i'm looking for this answer( maybe not that good )
Thanks