The Tang Dynasty's First Live-in Son-in-Law

He transmigrates to the Tang dynasty as a live-in son-in-law, only to learn that both his family and his father-in-law’s family will side with the rebels in the An Lushan Rebellion. Thinking of the rebellion’s tragic end, Li Xuan panics.

With less than half a year until the An Lushan Rebellion begins, how can he take control of his own fate in an age at its peak and already turning toward decline? Answer online, urgent!