Is estrangement from one's father considered a severance of kinship ties (qati'at al-rahim), especially if his behavior—such as abandoning the home and marrying a woman of ill repute—is rejected by his children, despite their attempts to advise him?

It is permissible to contend with the father to obtain what is due or to remove injustice, without arrogance, raising one's voice, or causing harm. Severing ties with the father is forbidden, even if he mistreats, and his mistreatment of you is not permissible. Treat him well and advise him kindly, or seek help from someone who has influence with him. His second wife is not allowed to harm you, and you have the right to respond in kind or to forgive. The father's attachment to her does not justify his disobedience or abandonment.