Co-consciousness for me was when any one of us was out and present in the world and simultaneously able to converse (internally) or be aware of what others were saying internally.
Here's a tricky concept: I only know what it was like for ME - I do not know what it was like from my alts perspectives. Did they even have a perspective on this? I don't even know.
There MUST be co-consciousness all the time at some level because how else would a particular alter be triggered by an external event? There must be some communication / co-consciousness going on somewhere. Maybe?
Let's say hosty person was out and about in the world and some trigger for alter q happened... either alter q had to be consciously aware of the external trigger event (otherwise how would he/she react to it?) or the

Okay someone tells me (co-consciousness of some form right there - I hear the voice in my head, but don't know who it belongs to) says yes they have to be aware all the time because they have to be able too get out BEFORE it gets bad so they have to be keeping an eye out for anything that could go wrong and if they see anything then they come out so we don't have to see it.
So there ya go. Co-consciousness to me is THAT - communication across the great divide.