I kind of feel like that doesn't really fit the game, and if you would like a specific event to happen at specific time, you can just manually do that yourself. So seems like too much work for something the player can manually do if they want
Bro why did you respond to this old message :D Anyway you can unity nations with the annex button, only diference is that name doesn't unify. I might add a separate unify button if I change how unifications work abit