请帮忙解释一下句中两个living 为什么用ing 形式

请帮忙解释一下句中两个living 为什么用ing 形式
So,it is still very common in today’s China to see married sons or daughters living with their parents.However,China no longer has the so-called four generations living under the same roof.
living with their parents 作定语修饰married sons or daughters 因为married sons or daughters 是live的主语，所以用ing 形式。另外第二个living没有给我解释。