Since you are receiving EDI inbound into webMethods then,you can extract/check those EDI duns values from the ISA level
ISA05(Qualifier),ISA06(Duns#) using envelopeProcess service and put a conditionlogic in your map.
If not please elaborate more info on your requirement…to do’s etc…
HTH,
RMG
#webMethods#edi#Integration-Server-and-ESB