Every airline is different, but you probably won't be able to get her an ID90 unless she's your designated domestic partner, and that's if your airline allows you to designate her as one, which is a big if at most airlines. Do you get buddy passes? Those work for almost anyone. If your airline doesn't go where you want to, maybe you could use a buddy pass to get part of the way there at least. But basically, consult your airline's travel manual or call your travel department.