Bonjour Gregoire,
Ce n'est pas beaucoup !
Ok with the combination of the von Eberhardt list and my databases I came to the following list. The way of working is simple. Take out bomming losses, take out thos who died while sick, who died later, crews that both crewmembers were killed, the ones killed in Germany and accidents, Jasta pilots, the pilots and this leaves us with the unknowns and the observers :
- Lt Kurt Finke, observer, + Amiens
- Gefr. Kurt Günther + Mantaigu
- Lt Siegfried Haupt, observer FAA 205 + Soissons
- Vzfeldw. Otto von der Heydt, FAA 278 + Baconnes
- Flg. Johann Marx + Fins
- Lt. Paul Steiner, observer FA 42 + Lommelet
The observer that died should be one of these six. And If Marx was indeed Flieger, it becomes on of five !
With just a little luck .... :

and some other helping hands on this Forum ? ???
VBR from Regulus