| You are correct, sir

Leaders cannot command other leaders. You can look at this rule a few different ways:

1) Rather than add a level of complexity to the rules where you need to pay attention to the rank of the different leaders and who can command who, it is abstracted out. This makes sense because if I recall there are only a few different levels of leaders, but many 'ranks' that are simply a fluff touch.

2) You can also look at it at a tactical level where I would imagine the officers have coordinated the battle plan in advance and know where and when they are coordinating their troops movements, so it makes sense within reason, that they cannot command each other.

OR

3) It is stupid and the game is broken.