I wish I could do that. My normal friend group from high school consists of five people, one over the normal limit.

There exists the AlphaRing mod for PC that allows local co-op and still functions online, but it's cumbersome to connect four players where one would, I guess, just be using parsec into their partner's game or something. And even then, we couldn't do Halo 1 since that never had more than 2-player co-op to begin with, meaning AlphaRing only boosts it to four.

I did play through the Bungie trilogy with my dad though, before AlphaRing was even out and you had to rely on nexus co-op. Even with the technical bugs it was probably the least-stressful interaction we'd had in years.