Storage location for vendor return

Dear Colleagues:

I have a scenario where my customer receive the material in block stock with 103 mvt type. Then if required return it with the mvt type 124. But some times vendor does not come to collect the material for 5-6 months and that material lies in the store with no identity. Now my customer wants to monitor this stock. So is it possible to do GR with 103 and then use non valuated mvt type to get the material in vendor return location. Once vendor comes to collect the material then I will return it with the mvt type 124.