I stumbled across the attached patch. IT certainly looks like a NSFK glider pilots achievement badge, but seems a cross bread between the known A grade with one wing and the more uncommon and unknown “Leistungsabzeichen” as shown in a copy out of one of the 1941 printed “Uniformenmarkt” magazines. Luckily a photo survived with an HJ member showing not only the C-grade of the NSFK patch, but the unknown ptach right underneath.
Anybody out there with more information? Is it possibly a HJ variation of the NSFK glider patch, maybe a higher grade?