Killing all of another factions family members

I am playing as the Byzantines and the Mongols have decided to come and make life difficult for my Islamic neighbors. I happen to have an army of assassins that I am fond of using and a family member of the Mongols asked me to kill his father Khan. I happily accepted his proposal and slew his father for him on my first attempt after having brought about 6 high level assassins into the area. Not wanting my assassins to be idle I decided to attack the other family members. To my surprise I killed all of them. :yes: By this point the Mongols had settled down and established themselves at Antioch and were no longer a horde in the BI sense but a faction. I was under the impression that killing all of the royal family of a faction destroyed that faction but this does not seem to be the case. Now it is possible that I missed one of the family members but I don't see how. I'm pretty sure I've gotten them all. Does killing the family members of a faction destroy the faction? In that case am I missing a family member or have the rules changed in MTW2 and a faction can exist without leaders to guide it? :inquisitive:

You need to kill them all. I've eliminated few factions myself using assassins.

It still works, Im in the middle of a byzantine campaign as well, and I got rid of Turkey by killing all their family members, after that they became rebels.

Chances are that there is just one family member hiding in a settlement somewhere.

Well I think figured out what happened. I think you can kill all the family members of normal factions and destroy them that way but not the Mongols. Now a new stack of only Mongol family members has appeared including a new 10 star general and is headed for Antioch. Only 3 members in the stack and they appeared out of nowhere. I think the game repops them. Searching for the family member i thought i missed has scattered my assassins and i will never get them all now. Worse their huge army is now attacking me even though we were on good terms before... i thought.

Mongols come in 3 waves with a total of around 10 stacks with corresponding generals. You need to kill all the generals of all the waves for them to be eliminated.