Regarding W4024 Check again using SE16 at table PGMI
the check is made in MMREO012 and this is calling FUNCTION 'MC_PG_MITGLIEDER_GET'
and this FM is checking at table PGMI
there is more coding for PRGRP checks in this MMREO12, if has to do with sales plan then the product group is check against an entry in table P445V