What is the largest possible Duchy of Carinthia?
http://en.wikipedia.org/wiki/Duchy_of_Carinthia
Have Anna of Bohemia survive causing Carinthia to be in personal union with Bohemia, however, they would need to give up their claims to the Polish crown by marrying their sisters to the son of the King of Poland, Elisabeth of Bohemia could marry Stephen of Poland as a way of getting rid of her as a rival.