receiving procedure for scrap against SC PO

Hi,

SC Po is prepared with BOM as usual with offgauge/scrap qty (-). In my scenario Scrap will be received afterwords and not with the output material. If I receive the material without BOM , and try to receive seperately against same PO , system gives message "Nil items left in the PO". Since scrap material will be in bulk(mine is steel industries) , receiving scrap material with output material is not possible. Pl let me know how can I receive the BOM material seperately.

Thanks & Best Regards,

Atul