Infiltrator action done?
Option 1: infiltrator caught, identity revealed, banishment or worse to be given in a few turns
Option 2: infiltrator free, identity revealed.
Option 3: infiltrator free, identity not revealed, proceed:
Step 1: Look at the nobles present in said region
Step 2: Sort nobles according to which realms they belong to
Step 3: Look up the family histories of nobles, starting by those without units and those of enemy realms and moving down the list towards the less likely. Say "bingo" every time you spot "banned by blablabla for being a lowly saboteur"
I don't "keep a list" of infiltrators. I don't recall the last time an infiltrator action was done in a region with more than 6 nobles without his identity being revealed automatically. Looking up the family histories really doesn't take any time at all.
Besides, what's plausible deniability good for anyways? Infiltrator actions don't increase skill when working in friendly regions, so you have to work in enemy lands. Infiltrator or not, you will be treated as an enemy there regardless. And if you aren't in enemy lands, and you are trying to cause a scandal? I've personally had my characters targetted by realm-mates and allies on various occasions. I never made a fuss about it unless it was my intent to do so anyways. A rogue infil isn't worth making diplomacy on. In reality, the plausibility is more a weapon of the attacked than the attacker: it gives one a lot of range to falsely accuse people he wants to frame. After all, usually the infils don't go around shouting "Hey, no, I was the one who attacked you!"
The whole "plausible deniability" shenenigans is really pointless.
