Hi Rajiv,
If form of SF part (getting new components, cutting in pieces, coloring,etc) is changing after subcontracting operations then its advisable to use different material.
Else if its just processing then subcon BOM can be created same component as SF part.
With the net price in subcon PO subcontracting valuation can be accommodated.
And for this have subcon operations maintained as external (control key).
Thanks,
Amit