@flyer
I’m not sure what you’re referring to. The first Sifsei Chachamim in the Torah reads as follows:
??????, ??? ????? ?? ???? ?????? ??? ????? ?????? ??????? ?? ??????? ????, (??? ?? ????? ????? ????), ?? ?? ?? ??? ????? ????? ?? ??? ?? ????? ????? ??? ????? ??? ???? ???? ??? ??? ????? ?? ??? ??????.
As you can see, not a word about Rebbi Yitzchok being Rashi’s father.
I even checked 2 other Chumoshim to make sure I wasn’t missing something, but they were identical.