Return Purchase Order (MVT #161) Sales Area Determination on Purchase Order

Hi,

I am working on return purchase order (Purchase order with return check box ON at item level) and creating outbound delivery with VL10B and doing PGI to vendor.

Can someone help to figure out how sales area (sales org/distribution channel/Division) gets determine on purchase order item level "Shipping" tab ?

In other word, as shown below for return PO, I have sales area 1180/50/01. I want to determine different sales area.

Thanks.

Regards,

Ravi.