However, his foster father became the leader of the Ouetsu-reppan alliance in 1868, and as a result, the father was ordered by the new government army to be placed under house arrest, when even Muneatsu was disinherited.
しかし慶応4年（1868年）に養父・慶邦が奥羽列藩同盟の盟主となったために新政府軍から謹慎を申し付けられたとき、宗敦も廃嫡されてしまった