[PeterL]

Gunnar, well I got my references back, and now I remember why I was so vague about this in my web article. The exact date or circumstances are not mentioned in either the English or the French accounts I have. Both mention it so it probably happened, and it must be a Morane because Guynemer doesn't get his hands on a Nieuport X until October. Presumably Guerder was in the back seat.
Such detail as I have states that he was shot down "in combat with an enemy formation." You can speculate as well as I, probably better, but I think it unlikely at this date he was attacked by a group of scouts. Much more likely he was attacking a formation of two seaters, it also fits his M.O.

hope this helps, but I very much doubt it.

Peter L