Wellcome to subsim!
Yes they are interoperable, and you need the official 1.1 patch from Ubisoft for that. But the stock multiplayer was not very good, so a programmer called Duane Doutel developed in cooperation with subsim a new patch, called "Projekt Messerwetzer", to be installed on top of that original UBI 1.1 patch, which improves considerably the experience.
1.1 should be available at UBI web
Projekt Mess is available here at subsim
I'm moving this topic to the "classics" forum as there's where the Sh2/DC stuff belongs.
