Add Editor that uses DDE to open files

How to add an Editor that uses DDE options to open files?
I haven't found a way to do so.
Some editors need it to work properly, unfortunately...

WinSCP does not support DDE. What editor are you using?

In the case, it is MS Expression Web 3.
I think it needs DDE to open pages in tabs. The system's default "Open" action uses DDE.
When the main exec is called, it opens a new instance and it takes much longer time than opening a new tab.

Ok. Will try it.