Dmitry Donskoy
Vasily Kosoy was the son of Yury Dmitrievich and Anastasia of Smolensk. His grandfather was Dmitry Donskoy who settled the issue of crown inheritance by passing a law according to which his oldest son Vasily I will become Grand Prince after his death and the second in line will be Donskoy's younger son Yury Dmitrievich. After coming to power Kosoy's uncle Vasily I changed these laws so that his sons became crown heirs and not Kosoy's father. This decision resulted in two civil wars between the older and younger Dmitry Donskoy line.