הלכה על יבמות 44:16

To not reveal the nakedness of his sister, from any angle that she is his sister: To not reveal the nakedness of his sister - whether she is a sister only from the father or whether she is a sister only from the mother; whether she is a sister from a woman raped by his father, or whether she is a sister from a mother from infidelity. From all of these angles, she is called his sister, and [he] is liable for her, as it is stated (Leviticus 18:9), "The nakedness of your sister - the daughter of your father or the daughter of your mother, whether born into the household or born outside." And if you shall say, "If so, what is this that is stated in the Torah (Leviticus 18:11), 'The nakedness of the daughter of the wife of your father, who has born into your father’s household'; and what was the need for this verse, is he not liable for her on account of [her being] his sister" - this verse was truthfully only stated to make the daughter of the wife of the father when she is his sister, a sexual prohibition on its own, and as we will write below in its place (below, Sefer HaChinukh 196). And it comes out that one who has intercourse with his sister, who is the daughter from the marriage of his father, is liable for two: on account of the nakedness of his sister and the nakedness of the daughter of the wife of his father. (Yevamot 22b). And if he has intercourse with her inadvertently, he is liable for two sin-offerings.