"Knowing this facts, I am not supporter of Klein & Quenzer AG, Idar-Oberstein theory, being producers of KO crosses. For me it was Klein, Oberstein. Klein probably returned to the Klein & Quenzer name only when EK production ceased and it was not from nostalgy. He just wanted to return to "civilian" international market under the same name as they used in prewar time and started to sell watches. chains and ladies jewelry as "good old" Klein & Quenzer."
we cannot know for sure, but I always thought after Quenzers death, or during his possible illness in 1917-18, maybe the Quenzer family was not sure they would continue with their share of the comapany? so old Klein was already angling for sole ownership and thought the company would be "Klein Oberstein", stamping crosses KO, then maybe the Quenzer Family said "We are keeping our shares" and stayed on as silent partners?
Just supposition, but you have to start somewhere...
The thing that intrigues me most is, how did the box and the crosses come together? It is of course possible that some Wehrkreis in the 1920s had hundreds of KO crosses left over after postwar awards had stopped and just placed them in this box which was laying around, totally unrelated to the crosses.... or they were all in another container and some collector put them in a box 10 years ago...
Either way, a stock of KO crosses must have been around, and at some stage someone put them in this box... in 1918 or 1928 or 1968... I guess we will never know :-(