If I were in her situation I would probably be jealous. You are telling her that it doesn't suit for her to live with you atm, but then you are getting a baby who can live with you. I know you must have your reasons, but to a 9 year old it must seem like you rearranging things for the baby but won't do the same for her.

I don't mean to be harsh or anything, just giving my opinion.
This is what I thought first too.