Is it forbidden for a man's son to marry the daughter of a woman whom his father contracted to marry and then divorced before consummating the marriage with her? And is the daughter forbidden to the father in this case? And is the woman's daughter forbidden to the man's son if the father consummated the marriage with the woman?

If a man marries a woman who has a daughter from another man, and he has a son from another woman, it is permissible for his son to marry her daughter, because there is no reason for prohibition between them. The fact that he is a brother to her sister has no religious text preventing the marriage. However, if the wife's daughter is of nursing age, and her mother breastfed her after marrying this man, some scholars hold that she becomes his foster daughter, and thus is prohibited to his son. Others, however, believe that she does not become his foster daughter unless her mother breastfed her after her birth from this husband.

As for the prohibition of the daughter to the father, if the intended meaning is the daughter of the wife whom the man married but did not consummate the marriage with, then she is not prohibited to him, because merely contracting marriage with the mothers does not prohibit the daughters. The stepdaughter is only prohibited upon consummating the marriage with her mother. If the question is about the daughter of the son's wife whom he has not consummated the marriage with, then she is generally not prohibited to the father.