You can't placate PUs, that's just for vassals only. Developing then should be used sparingly, because you'll also have to pay for their integration (and inheritable PUs usually aren't disloyal by the time your truce with them runs out), but in the case of the BI, when you get the land for free I agree it's a viable tactic.NB#1: Spending prestige and developing their land are tracked as two separate modifiers that will tick down at the same time. This means that, if you rely on both, then you will need to continuously spend prestige/mana to keep LD below 50.
- Improve relations to 200
- Spend prestige on the subject interaction screen to decrease liberty desire (if you have 81-100 prestige then you can decrease LD by 50 while paused)
- Spend your own mana to develop the subject's land
NB#2: You can't get more than -100 LD from spending prestige or from developing their land.
NB#3: If you got the PU from the Burgundian Inheritance event then you will probably inherit them soon. In this case, developing their land seems like the obvious best choice.
Outside of that though, it ticks down pretty quickly, their relative power increases, and you pay more for their integration later. Except when they are really close and you've done everything else in the book, I wouldn't do it, I'd rather dev my own lands to increase my power relative fo theirs.
- 2