There were at least two pilots with personal Edelweiss insignia:
Otto Kissenberth (20 victories), white Edelweiss on a black background
Paul Bäumer (43 victories), white Edelweiss on a red background
The only problem is that these two "cases" were neither Aviatik 2-seater pilots (they flew Albatros scouts) nor were these flowers squadron insignia.
Here is a photo of Kissenberths Albatros:
Hope this helps (but maybe I´m wrong)! *???