Su Liang did not go to inform Old Lady Xing about tonight's events. Although it would give her psychological preparation, or she could deal with some people in her family first, to avoid the emperor's punishment.
But the problem lies here. Su Liang is not sure what Duanmu Chen intends to do, and once Old Lady Xing personally deals with Madam Miao, Xing Yuyang, and Miss Miao, it would become a burden in her heart and would affect her relationship with the other children of the Miao family. In short, this is a very difficult situation to deal with.
Therefore, Su Liang did not want to pass this huge trouble to Old Lady Xing, and after the events took place, she only needed to say that Duanmu Chen did not allow her to interfere.
If Old Lady Xing doesn't know Duanmu Chen's intentions beforehand, can't stop him during the events, she will be able to let go more easily afterward.
