By part brother and sister, do you mean half brother and sister? In any case, yes, I would put them down as well.
I wouldn't go as far as putting sisters in laws nieces and nephews. Someone can correct me if I am wrong about that. I believe this form is mainly for information in case in the future, you decide to sponsor, e.g. your mother, or your brother wants to come over as skilled worker and wants to name you as a relative in Canada on their own application.
