In the circumstance that a minyan is comprised of people who all share an obligation to recite the kaddish, how is it said? Do they recite it in unison, skipping the amen at the conclusion of the first line but otherwise keeping in unchanged? Or is it integral to the kaddish that there be at least two people who are responding to it, rather than reciting it?
I say "at least two people" since subsequent amens are preceded by the plural ואמרו, and since the text uses plural suffixes on בחייכון וביומיכון.