Hi Anjana,
Use the converter Module in the EDI Separator Sender Adapter (handling 997). It will convert the 997 into xml. Once you have the xml you can use the ISA receiver id(target vendor id) xpath and use that as condition to route to VAN or AS2 receiver.
you can choose to have a mapping also (997 to 997) if you want to do some additional processing of the FA content - optional.
Again use the converter module in the receiver communication channels to convert the xml to EDI.
The only drawback of this approach is that you have to do conversion twice just for the purpose of routing.
Regards,
Sudharshan N A