I would suggest asking Forgottenlover as she is the ultimate authority on Doubles since its her baby. I'll tell you what I believe: Doubles has the five some plus Aru: Ed, Roy, Masuta, Riza, Al and Aru. Izumi knows about the fivesome (its in the notes for HoS). Her feelings on it is not expressed. But as cannon for HoS is VERY loose, you could run with it however you want. Ponytail would be a FL question I think.