Hi Jeff,
Maintain Material Groups in ECC via transaction OMSF or WG21.
Assignment Material to Mat.Group (UNSPSC) is made in Material maintenance transactions (MM01, MM02).
Check the link https://websmp210.sap-ag.de/~sapidb/011000358700000207252013E/OCI_50_EN20130228.pdf
That's OCI 5.0 Definition (Open Catalog Interface).
Could you please check page 13 and say, what fields come from vendor and how do the filled.
Regards
Konstantin