My daughter mistakenly claimed herself on her taxes.?

She received $500 tax refund. I started doing my taxes and show a $2200 increase in my refund if I go ahead and claim her, as by the rules I should. I ume the ISR will ask for her refund back, is this correct, or will they NOT process my return because her SSN# is already in the system? She's my 18 year old step-daughter, her mother and I are married and they resided in my residence for more than 6 months in 2008. She earned less that $2500 in 2008. Also she had a baby girl in June. What about my grand-baby?