Andre
Unless you know which staffel Steigleder was in when he was wounded, Remi is correct.
The Erg Staffel/NJG 1 was formed new in December 1940. In October 1941 this small unit was substantially expanded and the Erg Gruppe/NJG 1 was formed, mostly from IV.(Erg)/ZG 26. This expanded unit was also called IV/NJG 1. Erg.Staffel/NJG 1 then became 1./Erg Gruppe NJG 1, while Stab and 2. + 3. Staffeln were formed from IV.(Erg)/ZG 26. This 1./Erg Gruppe NJG 1 was also known as you correctly say as 10./NJG 1
Larry
10./NJG 1 is indeed a complicated unit. In all there were four different 10./NJG 1 between June 1940 and the final one formed in October 1942. Joop seems to have got most of his facts right although he fails to outline some of the small sundry units formed from the outdated NJG system still prevailing at the time. If you can get your hands on Meyer and Stipdonk's Die Deutsche Luftwaffe, Zerstörer und Nachjagdverbände Teil 1, I think they give the best explanation so far....., but you never know what's going to turn up....
Cheers
Stig