Shen Biran arranged for Gu Xiaonuan to have the best person, someone she could truly trust, by her side.
If Gu Xiaonuan doubts Si Yuchen, then there's no one in Sea City worth trusting for her.
This is the reason that led to the current situation.
Moreover, if Shen Biran lets Gu Xiaonuan discover Gu Qingyuan's conspiracy or becomes threatened by Lu Xiao, it would be incredibly irresponsible as a mother.
To help Gu Xiaonuan escape from this trap, Shen Biran is willing to use any means necessary.
As long as the immediate problem can be solved, nothing else seems that important.
Besides, Gu Xiaonuan is different from others; her feelings toward Gu Qingyuan are genuine. She isn't forcing herself to help him; she has always treated Gu Qingyuan as a father. This emotion is Gabriel's.
There's no other way; Shen Biran has to keep things from Gu Xiaonuan, even though Lu Xiao plans to take action, it wouldn't happen immediately.
