Responses

Technically it wouldn’t be incest because they wouldn’t be related by blood. For example: you have a sister and they get married to a guy he becomes your brother-in-law and he has a brother and you two are going out, it’s fine cause you two are not related, and the family knows each other cause his brother married your sister. It’s kinda like that, sorry for the long explanation
I just know it they're gonna be step brothers. Why it has to have incest in it