Can a step-son be a Mahram to his step-mother?
Can a step-father be a Mahram to his step-daughter or be considered as her father?
A step-son is a Mahram to his step-mother because he is one of her unmarriageable male relatives. A step-father who consummated marriage with the mother is also a Mahram to his step-daughter because (Part No. 17; Page No. 350) he is one of her unmarriageable male relatives. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.