Hi Sunil,
Each category is assigned to a purchasing group. And any incomplete shopping cart ordered, will be taken up by anyone of the purchaser/buyer in that purchasing group.
You can find the product category - purchasing group relationship from the function module BBP_OM_DETERMINE_RESP_PGRP . (pass category guid in the item data strucuture).
You can findout the list of purchasers / buyers of a particular purchasing group from the function module BBP_PDH_PUT_PGRP_TO_WEB . (pass purch group id).
So, any purchaser/buyer belonging to that purchasing group can take up and carry out sourcing activity for it.
Regards,
karthik