Is the hijab required from a stepson (rabīb) who has reached 13 years of age, knowing that the questioner and her daughters still uncover themselves in front of him?

The husband's son is forbidden to your daughter because she is his father's wife. He is a stranger to you and your daughters, and he is permitted to marry any of you. If this boy reaches puberty, he is treated as an adult with regard to the impermissibility of looking; therefore, it is not permissible for you and your daughters to uncover your faces in front of him, and you must veil yourselves from him. If he has not reached puberty, he is an adolescent treated like an adult with regard to the impermissibility of looking; therefore, the guardian must prevent him from looking, and you must veil yourselves from him, but he is permitted to enter upon you without permission, except at times when clothes are removed.