@HeavyMetal4Life - hopefully the present day vixen makes an appearence

@krayzeman - So Arrow, Flash, Legends, and Constantine all take place on Earth 1. But the Arrowverse, at least to me, includes the entire multiverse; I don't see any reason why we wouldn't include other stuff, especially if multiverse stuff appears in the "core" Arrowverse shows all the time (usually on Flash). So in addition to those 4 shows listed above, Supergirl is in the Arrowverse.

True, there could be a Vixen (and they are almost certainly referring to the present day Vixen, not Amaya) on Supergirl's Earth, or we could be talking about an entirely different Earth that has both characters. But I want to believe that they are talking about versions of characters we've already seen (until evidence suggests otherwise). And we've only seen Vixen on Earth 1. Regarding Supergirl, she has shown up for the past two crossovers, and between fending off an alien attack and a Nazi invasion, she's become a public figure (even if she's from another Earth). Remember, she was at the press conference after they fended off the Dominators. And the Nazi invasion was national news. So I don't think its far-fetched for people on Earth 1 to know about Supergirl.

Regardless of all that and which Earth it is on, the fact that those characters are mentioned almost certainly indicates its in the Arrowverse. Jennifer is asking her mom about characters that are known to the public. Black Lightning is a public figure, and Vixen and Supergirl must be as well.