It's not clear why the second lady is so indifferent to a fuck in front of her? And the little black lady - they took it out on her ass and she continues to lie there quietly and doesn't run to the bathroom to wash up? Maybe she means that she fantasizes about sex, but nothing really happened.
It's not even quite clear whether the brother helped his sister, pleasured her, or taught her. Either way, she should be grateful to him after a fuck like that. It's funny to see how he uses both his phallus and her toys to develop his sister's anal hole. It's bright and exciting, and you can see the details that are so valuable in a process like this. I wonder what he will turn her on with next time.
I'd do them both.