הלכה על יבמות 108:8

From the laws of the commandment is, for example, that which they, may their memory be blessed, said (Yevamot 54b) that the prohibition of the sister of the father is whether she is the sister of his father from the father only or from the mother only; whether she is the sister from marriage or whether from licentiousness - as each one of these is called his sister regardless. And there is no room for secondary [prohibitions] here.