Did someone implement AS2 with multiple attachements?

Now, we got a requirement from partner with Seeburger that they need to implement AS2 with multiple attachements.
But when I queried how to realize it in webMethods Advantage, I found no information. And in the webMethods forum, someone said the multi-Attachments is only an optional funtion for EDIINT, so webMethods did not support that.
After a few hours working, I did not get any official reply by advantage.
Now we are using webMethods 6.1 as our production server, and as you know Software AG will not give any support to 6.1 version as its lifttime retired.

So please help to check whether there is someone who once implemented AS2 with multi-attachments.
If the answer is yes, please give me a favor to clarify a simple instruction.
If it is not executable, please also reply.
Thanks a lot, I’m crying…

Best regards,
Polo Hou