Most of the documents of the family head had already been lost in a fire in 1542, and Sosetsu together with Motohisa worked to copy and organize the remaining works, which Juro Dayu had presented to Ieyasu.
元より宗家の伝書類は天文11年の火事でほとんど失われており、宗節は元尚とともに、十郎大夫が家康に献上していたこれらの著作を書写・整理することに勤めた。