Ruling on a man marrying his father's stepdaughter

Question:
Is it permissible for a man to marry the daughter of his father's wife from another man, whether before his father married her or after? Please advise us, may Allah reward you with good.

Answer:
Yes, it is permissible for a man to marry the daughter of his father's wife from a husband other than his father, whether before or after his father's marriage. A man may take a woman and take her son, or her daughter, and the reverse is the same; there is nothing wrong with that.

Question : Do you mean his father's stepdaughter?

Answer: His father's stepdaughter is forbidden to his father, but she is not forbidden to him; she is not forbidden to the son.