Hi Gunnar,
As far as I know KagOHL 1 consisted of 6 Staffeln in 1916 but was splited in two Halbgeschwader.
Halbgeschwader 1 consists of Kastas 1,4 and 6 and Halbgeschwader 2 of Kastas 2,3 and 5. Don't know about their action area.
In spring 1917 when OHL increases bombers, it was planed to recreate KagOHL 1 from Halbgeschwader 2 by adding 3 new Kastas.
The Kastas 1,4[37] and 5 were renamed to Kastas 13,14 and 15. With the newly formed Kastas 16, 17 and 18 they formed the new KagOHL 3.
But this new KagOHL 3 had nothing to do with the old KagOHL 3 from 1916 which Kastas became Schustas in 1917.
Very complicated isn't it?
Jörg Mückler wrote an excellent article about it a year ago in the german journal "Flugzeug".
Hope that helps,
Immo