971. Chasan Torah, Chasan Bereishis

138:8 On Simchas Torah day, the practice in many places is that the kohanim bless the congregation during the shacharis rather than musaf out of the concern that some of them may drink alcohol by the time musaf is recited. (In some places the kohanim duchen in musaf as per usual, but then they must not drink alcohol - Mishnah Brurah 669:17.) We do not say "v'sei'areiv" when duchening during shacharis.

138:9 Simchas Torah day, after the Hakafos, we keep three sifrei Torah out. We read for many people in one Torah from "V'Zos HaBracha" (Deuteronomy 33:1-26), repeatedly. (This is done to honor the Torah and to give everyone the merit of an aliyah - MB 669:12.) At the end, we call up all the youth, collectively. The proper way to do this is for an adult among them (when there is one - MB ibid.) to recite the bracha and for the rest to listen. We read for them from the section "hamalach hago'eil osi" ("The angel who redeemed me..." - Genesis 48:16).

After this, we call up the "chasan Torah" ("groom of the Torah") and read for him to the end of the Torah. In the second Torah, we call up the "chasan Bereishis" ("groom of Genesis"). We say half-kaddish and read the maftir from the third Torah. The practice in many places is to be scrupulous and to call a prominent person as chasan Torah. Even if one already had an aliyah, he may still be called up again as chasan Torah or chasan Bereishis. (The chasan Torah may not be called up as chasan Bereishis in the same minyan, although he may later, elsewhere - MB 669:2.) In a place where they have only two sifrei Torah, we read V'Zos HaBracha in the first, Bereishis in the second,  and we return to the first for maftir. (This assumes that it was rolled to the proper place in the interim. If it wasn't, it would be less of an imposition on the congregation to read maftir from the second Torah - Bi'ur Halacha 669:1 s.v. v'chozrin.)