A:
The act of those children i.e. cursing their uncle and grandfather is legally Haram (prohibited). It is not permissible for their father to remain silent, because their act is
a curse of a specified person and it is a severance of the ties of kinship and an offense to them. They should repent to Allah and ask for His Forgiveness; may He accept their repentance. Likewise, they should pray for their grandfather and uncle and be benevolent to those who are alive in order to help maintain the ties of kinship. They have to ask Allah to forgive them. Their father should advise them; perhaps they would accept the advice. May Allah guide all to success.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.