How does Xiaoyu exist in the TV series "Family with Children"?

For this family, Liu Mei's attitude towards Xiaoxue is flattering. Xiaoyu likes Liu Mei better because she is too young. Therefore, Liu Xing will suffer indignities. But in fact, she is also planning for Liu Xing's future. Liu Xing seems to be very happy every day. Many times, the happier people are, the more likely they are to be depressed. Many times, his happiness is an illusion. Few people really understand the difficulties in Liu Xing's heart, and his fucking words sometimes hurt him deeply. Because children have different personalities, it can be seen that parents are educating their children, and children with different personalities have different educational methods.