What should the questioner do about her divorced sister's daughters, for whom no one asks, and whose husband does not approve of them, and who are adolescents, and whom relatives are exploiting?

The financial support of poor children (both male and female) is obligatory upon their father, as he is responsible for them. He must take them in, protect them, discipline them, and educate them. It is not permissible for him to abandon them or neglect their material and moral rights. If they are of an age requiring custody, their custody is obligatory upon those entitled to it after their mother. You are not obliged to take them into your home unless you volunteer to do so with your husband's permission, for the Prophet, peace and blessings be upon him, said: "and she should not allow anyone into his house except with his permission." If the husband does not agree, then you are only obliged to advise them and maintain kinship ties with them as much as you can, while noting that it is not permissible for a woman to spend from her husband's money without his permission.