the B2B idea was something i too wanted to implement but ultimately didn't want to look too far ahead and bite off more than I could chew knowing the potential problems as mentioned below by the other commenter with latency, mixing and syncing, interpolation, extrapolation etc.. At that point I just decided to focus on 1 DJ / Producer doing a live set and essentially just live broadcast without any sync issues to handle as it wouldn't matter if the set was delayed.
But it would be so cool if that feature could be implemented. I hope one day somebody much smarter than me could work towards some of these features.