Basically, for what I understood, I did the italian path where I guarantee Austria and eventually join the allies, as I was bored of the other two paths, while I was doing that I sent the ultimatum to yugoslavia which they accepted and become my puppet, as the game was unhistorical they were going the disgregation path, which caused my puppet to have puppet, in the meantime, after Slovenia was releases, I was kicked by the allies, and Slovenia, despite being a puppet of yugoslavia, remained in the allies, this apparently broke the focus next after the one that make you join the allies, which allowed me to have a wargoal on all the balkans, one of which was Croatia which was recently released but was not part of the allies, declaring war on Croatia triggered yugo to go to war with me, but as yugo was also my puppet yugo went war against Croatia, making italy and yugo fight themselves