On Pesachim 91A, the Gemora thought that a group of youngsters can make a Korben Pesach. But a Korben Pesach needs to be done 'lishma'.
How can a minor do it 'lishma'? If it is sufficient that the Cohen does it, but then can the youngster make the Cohen an agent?
Thanks in advance,
Good question. According to the opinion (Nedarim 35b, Yoma 19a, Kidushin 23b) which holds that Kohanim perform the service in the Beis ha'Mikdash as agents of Hash-m (as opposed to performing the service as agents of the Jewish people), certainly the Kohanim do not have to be agents of the minors, and thus the Kohen, who is a "Gadol," may prepare the Korban li'Shmah.
However, according to the opinion which holds that the Kohanim are the agents of the Jewish people, your question remains -- how can children make a Korban Pesach, or any Korban? They cannot appoint agents to bring the Korban for them!
However, the Halachah follows the opinion that holds that the Kohanim are the agents of Hash-m, as the Gemara in Kidushin proves with a logical argument, and thus this Gemara is most likely following that opinion. (The Gemara in Kidushin did not prove this principle from the Mishnah in our Sugya, since according to the gemara's conclusion it is not referring to a group made up entirely of minors.)