Is Watanuki (xxxHOLiC) in Miyuki-Chan in Wonderland?

No, Watanuki Kimihiro from "xxxHOLiC" does not appear in "Miyuki-Chan in Wonderland." "Miyuki-Chan in Wonderland" is a manga series by CLAMP featuring a girl named Miyuki who is transported to various fantastical worlds inspired by "Alice's Adventures in Wonderland," but there is no crossover with the character Watanuki.