What is the ruling regarding the continued stay of a daughter who is married to a polytheist and has borne him three children, given that her father is now aware of this, and does any sin or responsibility fall upon the father?

It is not permissible for a Muslim woman to marry a polytheist. If it is proven that the man a Muslim woman married is an infidel, then the marriage contract is invalid by consensus, and the daughter must separate from him immediately without a divorce. The family must repent to Allah for their negligence. If the man is a Muslim but commits acts of polytheism, then the Islamic ruling must be clarified to him. If he repents, the marriage may continue; otherwise, separation between them becomes obligatory. In Islam, marriage requires a guardian.