Italy seems unformable even after only one candidate is left (screenshot from my France game, I loaded an earlier save and tagged over to see what was happening)
You need 15 of 17 Italian state regions to form Italy. Eating all the other Italians gives you 13. The other four are held by Austria. Good luck getting those (especially when player France has a defensive pact with A-H).
The best (perhaps only) viable solution here is probably to ally with Germany, whose army is reliably big enough to beat up multiple other GPs, but I'm not sure the AI is smart enough for that. I don't know if the Risorgimento buttons can create enough Italian activism in Austria to trigger a secession DP, and I suspect that would attract foreign intervention on Austria's side regardless.
Anyone got ideas for a solution? Maybe an event like the Dutch–Belgian London Conference to persuade other GPs to back the Italian claim?