how to change the version of BOM in the Subcontrating PO ?

Dear friends ,

We have one material that we send to Subcontrator via PO(Subcontrating process).

But some materials we have 3 version for BOM's. The standard is to bring the version 1 of the BOM.

How to change the version of BOM when necessary in the PO ? Is it possible ?

best regards,

Alessandro