Raemon: true - can´t argue about that 
In my case I just wanted a request/response function, and when I failed using notifiers (due to the issue in question) I ended up using the built-in mq request/reply function - which acually was alot easier.
tmac: If the request/reply function does not suit your solution, I would probably try something similar to what Raemon just suggested (assuming the back-end system can return the request id).
If you have a database with envelopes (from published documents waiting for replies) you can use the envelope tag or some other ID as a request id, and then use the same (from the reply) to retrieve the correct envelope before publishing you reply 
Best regards,
Mikael
#Adapters-and-E-Standards#Integration-Server-and-ESB#webMethods