GRN with out PO

Hi Experts,

I have a scenario and need your guidance to map into sap. My client has 2 company codes 1000 and 2000, from co code 1000 has to raise a PO for raw material V1 and that GRN should be happens in company code 2000. Here vendor distributes the goods to co code 2000 and invoice will send to co code 1000.

So how the system will receive the GRN with out PO and co code 1000 have one subcontracting with co code 2000 for this material. After collecting material V1 co code 2000 will do their job work and they will return that goods to co code 1000. Here what are the effects in FI.

If CIN is involved in this scenario, what are the steps i need to do regarding Cenvat credit. how to map this..

Thanks and regards,

Gamidi