Odd Behavior: Sardinia-Piedmont annexes all North Italian states in a mutual sphere with it

[Xylephony]

I have no idea if this is a bug or not, but whatever it is it's very unusual and doesn't deign to ask the sphere owner for any feedback. If you sphere Sardinia-Piedmont and either Lucca, Tuscany or Parma, Sardinia-Piedmont will eventually annex those states from your sphere outright (with Nationalism & Imperialism, I would guess, based on the timing).

This might actually be intended, but if it is it's still strange. These states should be required to be in Sardinia's sphere for them to be capable of annexing them outright without the sphere leader's assent. Whatever decision or event does this, it should probably require the sphere leader to assent, and block the annexation if they don't. When playing as France especially, it can lead to Sardinia-Piedmont rapidly inflating in size and becoming a GP just as a result of you trying to weaken Austria's position in Italy, which in turn has implications for your claims on Savoy.

[what-am-i-doing]

I don't think it's a bug, and I think it's a reasonable design decision. If you're France and you don't want Sardinia-Piedmont becoming a GP on its own, just don't sphere the minors. And if you're Austria-Hungary and you don't want the same happening, just don't sphere S-P.

Also, you can get claims on Savoy after Italy forms, if you didn't do Plombieres; the only difference is you then have to war for it and Italy will retain cores.

[Xylephony]

and I think it's a reasonable design decision

Why? I can think of no other circumstance in game where being in a shared sphere allows another power to interfere with your other spherelings, much less annex them outright. I have no problem with Sardinia-Piedmont being able to annex from within a shared sphere; indeed, I think it's a good feature. I have a major issue with them being able to do it without the sphere leader assenting, especially given that Sardinia-Piedmont starts allied with Austria and very close to being in their sphere, and as things are currently modeled there's a major, and irrational, risk for Austria if it tries to sphere them.

Also, you can get claims on Savoy after Italy forms, if you didn't do Plombieres; the only difference is you then have to war for it and Italy will retain cores.

Yes, and that's my point. Choosing to sphere the Italian minors to make the war with Austria easier can result in an Italy powerful enough that they refuse Plombieres and you have no recourse on Savoy but war. There's not a single thing wrong with that; it's a good thing that's a risk. But unless Sardinia-Piedmont is a GP itself or Pan-Nationalist rebels topple a government, there is no reason that I can think of that the sphere leader (France in this hypothetical case) should not have the final say. Even with governments as unpopular as the North Italian states and nationalism as virile as it was in the period, if push came to shove France could easily land troops to keep those governments propped up if it so chose to, yet there's no option to do the same as matters currently stand. They go to Sardinia-Piedmont and you're not even notified of it, not even that it could happen if they share spheres.

[what-am-i-doing]

If you get the Italian minors into your sphere you're bringing them together. The opposite of keeping them divided. They don't need your permission to unify - sphere of influence does not mean they're your vassals. If you want to keep Italy partitioned you should either sphere only some of it, or try to form vassals. You should view sphering both S-P and the other minors as basically bringing them together diplomatically and facilitating unification.

[ujtcelvn]

If you get the Italian minors into your sphere you're bringing them together.

This is the case elsewhere as well, for example, if I recall correctly, if you sphere both Argentina and Buenos Aries and they get merged together, and Rio Grande de Sol and Brazil and Pernambuco (I think) they automatically merge together as well, all without an option for you to stop them.

[Xylephony]

I suppose, although I truly don't know that I agree in the case of Austria. Sphering Sardinia-Piedmont is a matter of security for Austria, to stop them from declaring war, but doing so would wipe out their own Habsburg clients in the peninsula when clearly that's not in their best interest and, as regards their sphere, they would've absolutely done the utmost possible to prevent it. Sphering doesn't just represent closer diplomatic ties or markets, although it can and often does; it also represents matters of security and locking nations out from opposing you.

It's also further worth noting that I don't believe the same happens if Sicily is in Naples's sphere, if the two separate.

[Xylephony]

Also, as I just discovered, integrating Pernambuco is indeed a decision the sphere leader has, not something Brazil can initiate unilaterally.

[ujtcelvn]

Something similar happens to Romania too... I was making hypergermany as Austria and released Transylvania as a puppet, and then I puppeted Romania, and then Romania annexed Transylvania without a warning. Which, of course, is very stupid.