Particularly when streaming to Facebook, you'll want to leverage your own audiences when doing multi-artist streams.

What I recommend is either using the "Crossposting" feature (details below), or what I've nicknamed the "relay method" - where one Artist goes live to their Page, then directs their viewers to the next Artist's stream, like a digital pub crawl or a roaming dinner party.

• Don't leave out your built-in viewers by streaming your performance to someone else's personal profile. If you stream to your Page, they will be able to share it.
• Create a Facebook event, and add all participants as co-hosts (again, their Pages so that it shows up in their event timeline)
• discuss timing and direction with the other participants, so everyone knows what is happening and where to direct their traffic.
• In the Event Page, make sure guests know how to view the streams when they are live. It might be helpful to send out reminders ahead of time.
• While the streams are live, have all participants share each Artist's stream to all participants' Pages, with some copy in the share explaining that they are part of the show.
• Have a designated person share each Artist's stream to the Event Page while the event is taking place.
• Go a step further and have participants share each others' streams in groups, etc.

From a social responsibility standpoint, it might be wise to consider "social distancing" practices to lead by example, which is another reason you may want to do separate streams instead of getting unrelated people physically close together in one room.

Instagram Live has the capability to split-screen, so multi-artist shows would be a great use case for Instagram Live.

I mention throughout this course that you cannot "split-screen" on FB Live. When I say that, I mean "natively." It is possible using OBS. If you're planning to do this, definitely enable the Crossposting feature so that it will be viewed by both Artist's audiences.

Unfortunately, based on all my research and experience, it's nearly impossible to create a satisfying Livestream experience of multiple people trying to play together virtually from different physical locations at the same time, due to latency. If you know something I don't, though- tell me!

More Facebook info on "crossposting" -

https://www.facebook.com/help/678485232304895