I'm having a look at TEAW via the East Prussia scenario and tutorial.
I've managed to convert Hindenburg's stack into the OHL, but I can't seem to convert any of my 2-star Armee-Korps into actual *armies* (ie stacks with the diamond on their tab and so forth).
See the error message in the screenshot. https://photos.app.goo.gl/B3fPeErKLZNJUYoE6
Is this intended behaviour or am I doing something wrong? A GHQ without armies seems a bit of a waste since I would like to use the synchronized movement thing. Of course it does allow the creation of a Stack of Teutonic Doom around Paul von H, but is that all there is to it?
The tutorial also only converts Hindenburg to GHQ and does not demonstrate the conversion of stacks to armies.