Auto mix/auto ducking for multiple microphones in small studio

This is a situation I've run into before, but I don't believe it's an 'electronic' one, and I should say from the outset that I don't think you'll find an acceptable fix for it in Audition, if you don't like gating. From the sound of it, you have a situation where instead of just one mic in your recording space picking up room tone - which may be just about acceptable - you've got four or five, spread around the room. And when any one person is talking, you have them, plus all the phase issues of multiple mics at different distances from the source plus all of the extra room tone to contend with from the other open mics. I have to tell you now that it takes quite a bit of work to even minimise this, never mind eliminate it, and even in proper broadcast studios they tend to mute (or pull the fader on) mics that aren't being used, even if it's a group discussion. It's also normal for whoever is in charge of the group discussion to ensure that people don't speak over others, and this always makes things clearer for the listener; another strategy to consider. What it comes down to in the end is that there are probably several things you need to do to come up with acceptable results; it won't be just one thing.

I said 'quite a bit of work', but there is one thing that's relatively easy to do to a room, if you can get hold of some velvet curtains. Basically you need the area behind each guest to have the curtain hung - but there is one significant thing you have to do when hanging it, and that's to get it at least four inches away from the wall behind it. The simple explanation for this that when sound hits the curtain, it gets attenuated but some still passes through. This gets bounced off the wall and beamed directly back to the rear of the curtain, and attenuated again as it passes back though. So double the benefit, but you need those few inches of space for this to work properly. Just sticking acoustic foam on the walls really doesn't help - but most people don't realise that putting the foam on battens that spaces them a similar distance to the curtain spacing will achieve a similar result - for exactly the same reason.

Anyway, if you do that, then the sound from the person speaking won't be reflected back into the other mics at anything like the same level, and you'll have a much more 'peaceful' working environment to be in as well. If you've got people around a table, with the mics on it, then it's also worth putting some treatment on the table surface too, to minimise first reflections.

I hope that's some help. Feel free to ask more questions.