Everyone there lives happy/happily.
Are both the adjective and the adverb fine for this sentence?
Thank you in advance.
If you want to describe how they live, it's "happily."
You could say "Everyone who lives there is happy." But it's not quite the same thing.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.