<<Yeah, that was just a *little* weird. In
"Day of the Dove" we explicitly learn he was an only
child. That little hiccup almost lost us a match,
too>>
OK, letting my freak flag fly...
Worth noting,
according to the Star Trek Encylopedia, Chekov's "imagined"
brother was named Piotr (which I imagine could be
misheard as Cooter.) Chekov sought revenge on the Klingons
who he believed murdered that brother at a research
outpost.
CDB
Author of the other 2000 TRASHionals Star Trek Theme
Round.