Hi,
You can create a Standard Purchase order for materials for external vendor and receive it. Now for quality inspection you can create a Subcontract Purchase order another vendor and and send the materials another vendor (quality inspection) with t.code:MB1B with 541 movement type. Once quality inspection completed, you can receive material with t.code:MIGO with 101 movement type.
Finally,if quality OK for you- you can keep the material with you or else send that material to external vendor( material external vendor) with return delivery with t.code:MIGO.
Regards,
Biju K