You all, they: các anh, các chị ấy, họ

To speak to several people at once, put các before the family word you'd use for each one: các anh (you, to men a little older), các chị, các em, các bạn. For a mixed group, các anh chị. In everyday Saigon speech, mấy does the same job and sounds warmer: mấy anh, mấy chị, mấy em. Các is the careful and written form, and the usual one in Hà Nội. Careful: mấy also asks "how many" (Có mấy anh? How many of you?), and mấy người on its own, "you people", can sound rude.

For "they", add ấy: các anh ấy, các chị ấy. In Saigon you'll mostly hear mấy ảnh and mấy chỉ. For children, or friends you're close to, Saigon says tụi: tụi nó (they), tụi nhỏ (the kids).

Họ also means "they", but it keeps its distance. It fits strangers, people in the news, a company, or any group you aren't part of: Họ là khách du lịch. It sounds cold for your own family or for people you're close to, so there you repeat the family word: ba mẹ em, mấy chị. Don't mix it up with họ meaning family name: họ Nguyễn, and họ và tên (full name) on every form.