Since I think I want to avoid ludicrous situations where two commanders take turn and boost everything in sight including each other every other turn, I would rephrase this Ability to say:

"/.../(not including creatures with this special ability)."

Instead... makes more sense... unless you want some sort of chain-of-command effect where an Orc Captain can boost his Lieutenants but they cannot boost him back, only their subjects... but that is a little too much book keeping for me.

/wolf

I think that the quoted section is the key phrase here. Much of this game appears to rely on a modicum of common sense. To me, your situation falls under Loremaster fiat (as the Loremaster controls all adversaries) and can be avoided without the rewrite through a generous application of said common sense.

For example, how often are the heroes going to face a general and his lieutenants at the same time? Or multiple lieutenants at the same time, or in the same confrontation (however that is defined) for that matter?

Then again, could there be an example of this backfiring in the face of those that use the commanding voice? An encounter with too many cooks in the kitchen, maybe?