Daniel,
As Jürgen mentioned above searching for content and I would add to this testing in your sandbox should be done before starting to post questions like this. You best learn things by researching and testing. Then ask when you are really stuck and can't find any answer.
Here some help for you.
If you want to return directly from the subcontractor's location and thus return directly from subcontract stock you create a standard return PO and put into the delivery tab section of the item the vendor number for the subcontractor and check the SC vendor check box.
When you then process the return PO via say MIGO_GR the return will happen directly from the subcontractor.
