Sale-in-transit (e-1 transaction)

"A" is a seller in Rajasthan, "B" is the customer of A in Ahmedabad, "C" is the ultimate buyer in Ahmedabad. "A" raises an invoice by keeping "B" as the "Buyer" and "C" as the "Consignee". A charges 2% CST in the invoice. This is an E-1 transaction u/s 6(2) of CST Act. "B" raises a commercial invoice on "C" selling the goods by without adding any profit and charging any tax(subsequent sale is exempt). All formalities of E-1, C form and transfer of LR [u/s 3(b)] has been done between the parties. My question is: The CST paid is the cost of "B" or "C" ? Who will record the CST charged? "B" or "C"? Can "B" recover the amout of CST paid by him from "C" by separately charging CST of the same amount in the invoice of Basic Cost issued by him to "C"? Or will it be proportionately included in the cost/unit in the invoice?