1,950. Not Just Sisters
Yibum v’Chalitzah 7:21
Let’s say that a man’s daughter or some similar relative had congenital deafness. If she was widowed from his brother who had full faculties, his brother’s other widow must perform chalitzah to the exclusion of yibum because marriage was not fully effected with the congenitally-deaf woman.
Yibum v’Chalitzah 7:22
Wherever we discuss two sisters in the context of yibum, the same rules apply to a woman and her daughter or her granddaughter, or to any two women when one makes the other a prohibited relation. Similarly, wherever we discuss the sister of the surviving brother’s wife or the sister of his yevama, it also includes that woman’s mother or daughter, or any other relative who becomes prohibited because of her.