Why did Yu Shaoqian help Mu Yajing like this?

How did Mu Yajing hook up with Yu Shaoqian? Didn't Yu Shaoqian know that Mu Yajing had also a son?

Liu Yuyu's head was agitated.

Yu Shaoqian definitely did know that!

Mu Yajing concealed Yu Shaoqian, and then used the means to