Use Case: I'm streaming on my PC, playing games, etc. I want to go out for lunch, and instead of ending stream, now with the Mixer Create app, I can stream from my phone. Instead of ending stream on my PC, I can "take over" broadcasting on my phone, do lunch, etc., then later "take over" broadcasting on OBS when I'm ready to game again. This would be one smooth way to stream, instead of chopping up either thing and sending multiple notifications via Constellation service or emails to people.
In my test case, I used OBS to stream, then started Mixer Create's broadcast on the same channel. Both said live, but only the OBS stream showed on my page. I then stopped the OBS stream, and my channel went offline for a few seconds (8 or 9 seconds?), then the Mixer Create stream (which still said Live) started on my channel.