As far as I understand you can only promote the leader of a stack. And when you do every other leader in the stack, that is eligible for promotion, also gets promoted.
I just have had a big battle, and several of my generals are up for promotion. But the enemy is not definitly beaten, and in the next region. The *** general in command of the stack is not eligible for promotion. So if I want to promote those leaders I need to split the stack in the seperate brigades. Not good if the enemy attacks - and I certainly cannot attack the enemy if I do that.
On the flip side, I promoted a ** general a few turns earlier. I didnt see that a * general was also up for promotion. The promotion of this * general angered quite q few other generals, and it cost me NM and VP.
In short: I would like this game mechanism to change so I can promote generals that are part of a stack, and don't need to promote every eleigable general in the stack at once...