The forces of the Yamana clan, however, grew much more rapidly than Katsumoto had expected, and Katsumoto considered the expansion of Sozen’s power dangerous; therefore, when rivalry for the head of the family (the Buei disturbance) occurred in the Shiba clan, Katsumoto supported Yoshitoshi SHIBA, who fought against Yoshikane SHIBA, while Sozen supported Yoshikane SHIBA as they were related by marriage.
しかし山名氏の勢力が勝元の想像以上に急速に拡大したため、勝元は宗全の勢力拡大を危険視するようになり、斯波氏の家督争い（武衛騒動）でも姻戚関係から斯波義廉を支持する宗全に対し、勝元は義廉と対立する斯波義敏を支持した。