im so confused ive had generations since it came out but i never had the patience to
play a family for that long now im doing a legacy and i want to know if prom is possible every time and if multiples all go to prom at the same time ?????

I believe every teenager gets a prom (though whether every one of them attends such, is up to you). I dont know about in the case with multiples though, I've never played any yet.

I'm pretty certain that if you have more than one teen in the household, they all go

Yeah they all go, unless you prevent them.

I've always had multiples and yes they all go.
Anyone who is a teen will go.

Today I had boy/girl twins go and they ended up as prom king and queen. Maybe because the guy ended up being invited to go by another guy...it was funny though! This is my legacy style family and the twins are about to grow up so I'm deciding whether to let the guy marry his boyfriend when they are both adults and move out, and let the younger brother become heir instead. For my theme it needs to ideally be a male heir.