You appear to be asking two different questions. The first is how people deal with the person so diagnosed. The second, if I understand you correctly, is how to talk to the families. Two different things, but not necessarily two different answers.
The answer, really, is LOVINGLY. Kindly, gently, respecting where individuals "are" presently. If your friend is in a schizo phase, deal kindly. If the family are anxious, concerned, tearing their hair out, deal kindly. If you can't say anything, just be present, available, and quietly helpful. And silent.