The challenge with sending to multiple platforms at one time is
1. bandwidth
2. encoding requirements (as not all platforms support same settings) in which case there is a plugin (I think) to support multiple stream outputs, but now you take a really demanding real-time video encoding task, and multiply it by multiple streams (so depends on hardware and other)
- the alternative is to use a (pay) service, like restream.io to send you stream to, and that service will send to all the platforms you specify. You trade cost of service for local hardware requirements to do it yourself, and the bandwidth associated with sending multiple streams (depending on number of stream targets, many consumer ISPs may not provide that much upload bandwidth to support such traffic... depends)
so in a different context, I had to decide similar (which and # of platforms to stream to). My recommendation (which was followed) was to point users on other platforms to go to a single platform so user interactions would be consolidated (sense of community). For this reason, we went with Scheduled FB events as that creates a standard URL (for EVERY stream) that does NOT require a login to watch (one does have to login to comment, as is appropriate/reasonable)... but at least users aren't forced to have a FB account and can still watch. With the same URL every stream, our users can set up TVs to be able to see stream on big screen. I'm not advocating FB (which I generally despise)... just that a SINGLE platform may be advisable, depending on your audience
Just post notice to alternate platforms indicating stream about to take place
