No facilitator is needed. Then Side B converses while others watch. Then other sides or no-sides take their turns. The whole sequence repeats two or more times. Facilitation is often useful.
Someone needs to ring a bell to signal shifts.
Open Space Conferences - Participants who are passionate about a given topic create their own sessions on aspects of that topic. Active facilitation is needed at the beginning. Consensus Process - Explore a topic and options until all agree on the best approach. Facilitation is advisable.