Apparently viceroyalties are hardcoded to use primogeniture, ignoring duchies' succession laws. Well, that explains why I keep seeing vassals with 6 "gavelkind" duchy titles and landless siblings.
After a few generations that resulted in some horrible vassal bordergore - and AI is not bothered in any way whatsoever by "too many duchies" opinion penalty with vassals. Well, time for some modding to make it use gavelkind instead. I feel vassal succession should just be a realm-level law, per-title succession feels just silly, even though it had occasional historical precedent.
So I reset them to all use gavelkind, things should sort themselves out eventually.
I decided to crush Sunni horde of Trebizond, as I prefer Orthodox minors to another Sunni blob.
My husband Gelduin king of Burgundy died, so his son Sigismond inherited, betrothed to my daughter Better - so now my grandson is next in line.
I married heir to Mongol empire instead - and started seducing, aiming high at claimant to Aztec Empire. My lover then decided to lead host invasion against his brother, which inevitably failed.
Sunni Caliph declared jihad for Jerusalem on Egypt. I sent troops who lost huge 30k vs 30k battle for Tiberias, but second expedition captured the caliph and ended this silliness.
I continued pushing my claimants for countries such as
- emirate of Algrave - reverted after usurper had accident
- emirate of Arabia - failed as claimant died mid-war
- emirate of Medina - claimant installed
- what was left of Deccan Empire - claimant installed, then flipped Hindu due to educator, heir still Buddhist for now
- kingdom of Gujarat / Malwa - Gujarat taken, Malwa and Gujarat are each other's heirs; revolt to overthrow him already winning so he probably won't last
- sultanate of Syria / Caliphate - taken, then lost it to claimant before I could do anything; I helped rebellion overthrow caliph, but caliph's Sunni son is now in charge
- emirate of Mesopotamia - claimant installed
That was my first invasion of India. And with three different epidemics covering almost whole target country, there was no good place to land.
I messed up with succession of Punjab and Delhi as well, so with some luck the whole India will flip Buddhist - at least on the top.
My claimant to Medina needed immediate defense from Sunni holy war.
Overall this largest expedition ever attempted succeded in flipping 1 county Mesopotamia, 6 county Medina, and even that is rather unreliable. And the only thing I can do is to follow it up with another.
Kingdom of France ended, with mix of Buddhist and Catholic minors taking its place. Now they're fighting each other.
Indian strategy against invaders is bad hygiene
And they say games aren't realistic
The biggest rebellion in history, somehow did not succeed
All the meddling has very limited success