I just had an idea, and I wonder if that would be possible:

When a character is receiving the "Faction leader" trait, check out his influence and other abilities, and on that basis, give a certain chance that a rebel stack (preferably a big stack) with a character will appear near the capital.

In that way succession troubles could be simulated. If a character has eg. influece 10, management 8, the chance could be very low that a rebel army would spawn. If said character has influence 3, management 5, chances could be 50% of 60%. If he has not one influence or management, chances of a rebel stack to spawn should be 99%.

I think that's quite realistic, and an easy way to implement that feature as well. What do you think?