Any quick way to mod down traitors ?

[bisthebis]

I had stopped playing EB2 for a while for various reasons, but since 2.2 I started again. (and BTW, this update is wonderful)
But the only thing that, to me, breaks immersion, is unloyal leaders that break apart anytime they can.
In my ptolemaic game, my heir with a full stack joined eleutheroi by turn 10, while besieging damas.
In my roman game, by turn 45, I send my praetor with a full stack on rhegion and he turns eleutheroi. I should have destroyed this city sooner :p

I do not mind being corrupted by my ennemis, but eleutheroi corrupting everybody breaks immersion to me (Well, you'd say a roman legion being sent to conquer rhegion and then rebelling feels legit, but still :D)
Is there a quick way to reduce likelihhod of this, at least with eleutheroi, in a save-compatible way ?

Otherwise, do you have any strategic tips ? I've always thought only small stacks rebelled often...



EDIT : To be perfectly honext, I must admit than fighting my traitor's legion with a new one and killing the traitor was one of the most entertaining thing I've done i a while :)