Even though Su Xin decided to go to the Su Family with the intention of acknowledging his ancestors, he actually didn't feel any affiliation with the Su Family.
Just looking at the attitude of people like Su Zhongwei would tell that most of the Su Family members were beyond saving.
However, Su Xin was not worried that someone in the Su Family would plot against him secretly.
There were smart people in the Su Family, such as Su Mingyuan, who represented the reformist faction of the Su Family.
These people understood the logic that if the Su Family were to establish a strong foothold in the Jianghu, they must find an influential ally.
As one of the Four Great Divine Constables, Su Xin was indeed a heavyweight, thus within the Su Family, Su Mingyuan would protect Su Xin at all costs.