So this year's SuperFlarrow crossover is called "Elseworlds".
"Elseworlds" is actually the name of a line of comics that tell stories outside of regular continuity.
One of those Elseworlds stories was called "Kingdom Come" and included a Legion made up of other Legion members' offspring. This is where XTC - Brainiac 5 and Supergirl's daughter - comes from.
Since Barry/Iris got to meet their future daughter, wouldn't it be fun if we get to meet Brainy/Kara's daughter?
I doubt that's going to happen, but I figured it was worth putting out there
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