If you read Gebhard Aders «
Geshichte der Deutschen Nachtlagd» (or its English translation) you'll find a complicated story. IIRC, NJG 11 was formed from pieces of NJGr. 10 and was never a complete Geschwader. Its main aircraft was the Bf 109 G. By early 1945, there was only the III. Gruppe, I think. Kdo. Welter was renamed as 10./NJG 11 and by the end of the war, only it and the 7. Staffel still existed.
Try
this link and then select "Appendix 6" or
http://www.ww2.dk/air/njagd/njg11.htm