Integrate Title Contract For Free

If there are places that are de jure part of your realm but currently controlled by a neighbor, you can stick your steward there for 4-5 years "convincing" the local populace to demand to be returned to their "rightful" ruler (you, of course).

You may be emperor AND king, unlike too many duchies there is no too many kingdoms limitation. So you technically can hold all the kingdom titles under your empire or empires. For the reasons you listed it is better to have counts as direct vassals and not create duchies, until you hit the direct vassal cap.

In short, to get Titles In Crusader Kings 3, you will need a claim on it and a Casus Belli, and you can get both mainly by fabricating a claim via the Court Chaplain council member.

You can destroy titles without primogeniture, and the only succession law that recreates them is confed. Destroying a title is an effective way to not lose it with the other partitions. So you don't need primogeniture to do anything with titles.

It is not possible for counties to de jure drift, and so our above example would not see Dorset shift away from the de jure duchy of Wessex. However, duchies can de jure drift from one kingdom to another, as can kingdoms de jure drift from one empire to another.

Then so long as all the laws of both titles were identical, the holder would gain an "integrate titles" decision that if pressed would instantly make all the de jure land of the merged title de jure to one's primary title.

Have only one type of your highest title. If you highest title is a county and you have multiple of them then yeah, you're going to lose them in the succession. However, if your highest title is a duchy, make sure you only have one duchy title.