A picture of a/the local cemetery at Cartigny, France, with the grave of Lt. Frederick Grey, Sgt. Raymond Mears and Sgt. Frank Bartho here:
http://www.aerosteles.net/fiche.php?...ype=ps&lang=fr
On the other hand, there are also graves for these men in Iowa (Lt Grey), Maryland (Sgt. Mears) and Henri-Chapelle (Sgt. Sgt. Bartho).
Regards,
Leendert