I know that the primary approach to multiples in our society (once it was even admitted that they could exist!) was "reintegration", the goal being to merge them all back into a single personality. I don't know if that's still the case (and in any event, I would expect Terramagne to be better about this), but even the fear of it would be pretty stressful. It's like asking all the other personalities to willingly commit suicide!

The system needs to have a house meeting about this, because this sort of thing is going to come up again; it got nasty this time because they didn't have a plan to handle it, but that can and should be changed. In the specific case of Heron, perhaps the next time they know he's coming over, Clement can take front before they come out into the public areas? That way they wouldn't be actively switching in front of someone who might notice the energy shift. Not a perfect solution, but at least one that minimizes the risk.