Liang Ju was not directly related to the Li family, but his wife's sister was married to Li Muyan, a distant relative of the Li family. Li Muyan's sister, Li Xiangxiu, was married to Luo Shaodeng.
It is not appropriate to talk about the complicated relationships with everyone now, so they can only say that they are investigating the sister-in-law of Liang Ju, which makes it sound more reasonable.
Everyone split up- Su Xinyi, Zhan Qiao, and Wu Shun dressed in men's clothing and slightly disguised themselves, before heading out.
Even though Li Muyan's family was a branch of the Li Family, they had drifted apart from the main branch over time. Li Muyan, however, managed to get closer to the main branch again, so thanks to the Li family's connections, he married the second daughter of Governor of Ru State, He Qi.
The reason he went to great lengths to marry He Qi's younger daughter was because He Qi's elder daughter had married Liang Ju, the Commander of Wo Xiangwei.