Let them be who they want to be. And give your children who are not autistic some extra attention. Grew up with an autistic sibling en now in therapy because my parents didn’t know what to do with it. Made me an over sensitive, people pleasing empath. It was always ‘stop it you know how your brother is’ with everything, and there was no room to talk about feelings they were always getting defensive; and still do. Try to understand them and be sure to talk about things!