If they are closer to Ft. Worth, consider Country Day, Trinity Valley or All Saints- all in Ft.Worth and co-ed but good schools.
Thanks all for the replies. They are actually in Aledo ISD which is west of Ft. Worth. I am home visiting family right now and we talked about it today. She was very interested in in Hockaday but said that the commute just wouldn't work. What is the strongest co-ed school (in terms of academics) in Ft. Worth?