Hello,
The plugin "paypal adaptive" is made for that.
It will override with the vendor paypal email (if configured) and handle the sub-order.
If the vendor does not have a paypal, the store will receive the money and the payment process will be just like with the classical paypal plugin.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.