MobileConnect - Sennheiser Business Solutions - English | Sennheiser 

I guess there is no system in place for that - it'll just work the way it will with two people holding two microphones. Plus, the audience member perhaps goes through a request-approval flow before being granted mic access.

​@@thedipsomaniax yeah a system to give approval would be great. I can imagine people heckling the presentation if acces is too easy