In the mishna 8b, what's the case of ochlim merubim that you bring many chagigas? If you have many guests or sons over bar mitzvah, aren't they each chayav individually in chagigas and reiya? And if it's a case when they decide to bring it b'shutfus, why does R Chananel say that they want meat, Teipuk Leih úéôå÷ ìéä they need it to fulfill their chiyuv.
I found, bs'd, that this question is asked in the Sefer Ikvei Aharon, by Rabbi Yaakov Wahl, on Maseches Chagigah 8b.
1) He cites the Mar'eh ha'Panim, on the Talmud Yerushalmi, who writes that the "Ochlim Merubim" are "Semuchim Al Shulchano." This is a phrase that also appears, for example, in Bava Metzia 12b, and indicates that these people are financially dependent on the householder. Presumably they are not capable of buying their own Chagigah and Re'iyah.
This can also explain the case of sons over Bar Mitzvah if they are not yet breadwinners.
2) I would like to suggest an explanation of what Rabeinu Chananel says based on the Mishnah at the beginning of the Masechta (2a), that women are exempt from the Mitzvah of Re'iyah. Rabeinu Chananel is referring to a family where everyone likes eating meat on Yom Tov even though some of them are exempt.
To support what I wrote above, we note that the Mishnah is discussing a generous host who wants everyone to enjoy their Yom Tov celebrations and do more than the minimum. If everyone would eat a k'Zayis of meat, they would fulfil their Chiyuv but our householder wants everyone to feel relaxed and not be stingy. This is why Rabeinu Chananel writes that they all want to eat meat on Yom Tov. This suggests that they are doing more than the minimum requirement.
Kol Tuv,
Dovid Bloom