legal ground
Article 1072 of the Civil Code of People's Republic of China (PRC)
There should be no abuse or discrimination between stepparents and stepchildren.
The provisions of this law on the relationship between parents and children shall apply to the rights and obligations between stepfathers or stepmothers and their stepchildren.
Article 54 of the Supreme People's Court's Interpretation on the Application of the Marriage and Family Part of the Civil Code of People's Republic of China (PRC).
When the biological father divorces his stepmother or the biological mother divorces her stepfather, if the stepfather or stepmother does not agree to continue to raise the stepchildren who have been raised by him, they should still be raised by the biological father or mother.
Article 55
After the divorce, if one of the parents requests to change the child support relationship, or if the child requests to increase the child support, it shall be prosecuted separately.