1, maintain family harmony. In the traditional family in China, the relationship between brothers is very close. Big brother is responsible for protecting and taking care of his younger brother. Mutual respect, love and support are the basic tenets. The two brothers' families require the eldest sister-in-law to be like the mother, so as to better maintain family harmony, promote the feelings between brothers and make the family more United.

2. Inherit the family culture. In the traditional culture of China, the continuity and inheritance of family culture are emphasized, and it is believed that the prosperity and development of the family need the joint efforts of all family members. The concept of eldest sister-in-law as mother is a concrete manifestation of inheriting family culture, so as to carry forward family style and family training and make the family more United and powerful.