Not possible to charge via standard cost of raw materials

You requires the following requirement about costs on third party
subcontracting:

For third party subcontracting, the Puchase Order and the invoice cost will always only
have the subcontracting fees and not include the cost of raw  materials.

However, you want to charge the cost of raw materials used in the
subcontract process to the customer as these also constitute the cost
of the finished goods material.

Check information about the subject in SAP/KBA below:

2200601 - Cost on third party subcontract for raw material and finished goods

Best Regards,
Christian Rosa