Are the children of the ex-husband's family, and the sisters and brothers of the ex-husband, considered relatives such that ties of kinship must be maintained with them after divorce?

Kinship ties (Silat al-Rahim) pertain to relatives from both the father's and mother's sides, and include: fathers and mothers, grandfathers and grandmothers, children and their offspring (males and females), daughters' children, brothers and sisters and their offspring, paternal uncles and aunts, and maternal uncles and aunts and their offspring. As for the relatives of the wife and husband, they are in-laws (as'har) and not kin (arham), and maintaining ties with them does not fall under the category of kinship ties. It is obligatory for a woman to observe hijab from adolescent male children who can discern women's 'awrat (private parts).