Goods Receipt in Subcontracting process

Hi,

I am beginner in SAP.

This is regarding Goods Receipt in Subcontracting process.

I have provided raw material Quantity = 100 Nos. to subcontracting vendor.

Subcontracting vendor done machining on 80 Quantity, and we have done Goods Receipt for 80 Quantity as Finished Parts.

Subcontracting vendor found 20 Quantity as Defected.

Shall I take back 20 Quantity by Movement Type 542.

OR

Shall I do Goods Receipt of 20 Quantity as Finished Product and price = 0. & then stock transfer of Finished to Raw Material.

Please reply.