To me "Ms" always seems to indicate the person using it is insecure, or at least they they believe there is something inferior with one or other of the traditional titles.
I use Ms, have done so for years my marital status isn't anyone else's business. My daughter has used Ms since she was 16, for the same reason. Ms has nothing to do with divorce, and I'm not insecure. I also have never changed my name, don't see why I would.
Back to this plane issue, I feel the simplest solution is a tick box for "adult" or "child". Doesn't need to have any connection to titles, and doesn't need to tie to a DOB, when different countries use different dating styles.