[quote=@Rare]
Could Serbia make a leauge with both Croatia and Bosnia?

EDIT: I realize that Romania and Bulgaria joining the leauge is unrealisti...
[/quote]

For any form of league between Serbia, Croatia, and Bosnia they have to agree to a south slav Union under Serbia. Serbia would be willing to go democratic(although they still be authoritarian) if they could get the other two to join peacefully, not so sure about Bosnia but I doubt Germany would so willingly let Croatia join anything involving Serbia.