Are the children sinful if they do not visit their paternal grandparents after being expelled from the home and their father refusing to see them?

It is not obligatory for a child to obey his parents in divorcing his wife without a legitimate Sharia (definition) reason. Whoever prevents their children from visiting their grandparents is sinful, because cutting off kinship ties should not be met with a similar severance. The Prophet, peace and blessings be upon him, said: "The one who maintains ties of kinship is not the one who reciprocates, but the one who, when his ties of kinship are cut off, he re-establishes them." Whoever swears to cut off kinship ties must offer expiation for breaking an oath.