He's not horrible to her, so of course he would accept them. He just might not be the affectionate Bill from the books. And he likes her so much more than he does his father, he just doesn't like that they split the siblings up like they did. He resents that the most. And he hates his step-mother with a passion. I don't think he'll ever forgive his father for marrying her, but he was glad he has two new siblings from that coupling. (He likes Blaise and their half sister, but can't stand their parents.)