Do you really want the answer?

You keep asking my daughter if she even wants to be [visiting] there with her dad, and you, and your child with her dad, i.e., my daughter's half sister 8 years younger.
You're not happy when she doesn't answer.
She's trying to be polite; she doesn't really wish to hurt your feelings (and is also a scared to speak it out loud to you).
Every time you ask her, she's that much closer to giving you the answer.
Please don't be mad at her when she does.