I agree with the two previous posts.
Gracie Jolie is rhymey which just adds to the over-cutsiness of it being
Gracie and not
Grace. Yes,
Gracie is adorable, but I think it ought to be her nickname, while her full name is just
Grace. Much more professional and grown-up.
That being said, and considering the brothers' names, I'd go with
Grace and...
AbigailAnnaAvaClaireEllaEmmaKatherine (or maybe
Catherine so
Grace isn't the only non-K one)
LilyMadelineMaia /
MayaMeganMollySophie
Or if you really are set on
Gracie, then something that's also nicknamey I suppose:
AbbyAnnieBelle /
BellaEllaEllieKatieMaddieMaggieMiaMollySophie