I can't help with that, but have a little story.
My Grd-Mother was a teacher in a small village, the school was (still is) also used as the town hall. That building had an attic full of old stuff when i was a kid. Me and brother liked to check what was there in the dust for hours. We still have a wwII US helmet found there, but there was other things, like MG34 ammo boxes, mauser ammos... And lot of papers.
One day i found a very nice pencil portrait, it was a guy wearing kind of a furr flying helmet, with a signature i couldn't decypher...
Brought it to my father , who showed it to one of his friend , local glider pilot club president.
Turned out it was a signed Guynemer portrait . To my horror, my father gave it to the guy...
I know were it is now, but never had the occasion of seeing it since then.
