Can a latecomer recite Kedusha?

The Shulhan Aruch (Orah Haim, 69:1) discusses a case in which people prayed Shaharit individually because there was no Minyan and then a tenth person joins them. In such a case, one person can serve as a Shaliah Tzibur of sorts, and recite Kaddish, Barechu and the first blessing of Yotzer and thus everyone present could at least merit reciting those portions of the prayer with a Minyan. This procedure is known as Prisa (lt. “slicing”), since one is slicing the prayer into smaller parts, as it were. Rabbi David ben Zimra (Shu”t HaRadbaz, vol. IV, §241) rejects this approach and says that once everyone prayed individually, those parts of the prayer that require a Minyan cannot be recited.The Mishna Berura (M.B., O.H. 69:1) and the Ben Ish Hai (Rav Pe’alim, vol. II, Orah Haim, § 26) concur with the Radbaz. Although Rabbi Ovadia Yosef (Halichot Olam, vol. I, pg. 197) seems to side with the Shulhan Aruch’s ruling, the mainstream Sephardic approach is that Prisa is not performed, since the recital of these blessings might be done in vain. Furthermore, Rabbi Shalom Messas (Shemesh Umagen, vol. III, § 18-21) writes that the Moroccan custom is also not like the Shulhan Aruch.

There is, however, a custom which is universally practiced among Sephardic communities in which a person who missed the prayer with a Minyan can recite out loud the first three blessings of the Amida including Kedusha with the congregants who already prayed. Although it is not practical to wait for the person to recite Barechu and everything after it, this procedure affords one who arrived late the opportunity to recite Kedusha with a Minyan.  The Radbaz in this case would agree with this custom since the person did not yet pray and is allowed to recite Kedusha so long as there is a Minyan to respond. The Ben Ish Hai (ibid.) and the Kaf HaHaim (K.H., O.H. 69:1, 7), citing the Ma’amar Mordechai concur and indeed this is the Sephardic and Moroccan custom.

Summary: The Moroccan custom is unlike the Shulhan Aruch and that Prisa is not performed if a Minyan is formed after the congregants already prayed individually. The Moroccan and Sephardic custom is that if one missed the prayer with a Minyan, one may recite the first three blessings of Amida and the Kedusha with those that already prayed.