That is correct that a dependent cannot claim a dependent. It wouldn't benefit her at all. Also, since she earned less than $4,050 for 2016, you can claim her if you paid for over half of her expenses for the year. The only concern would be if the father is entitled to claim his child. Go through the dependent section in TurboTax (read the blue text links), as it does a great job of determining who qualifies as a dependent.
Who Can I Claim as a Dependent?
https://ttlc.intuit.com/replies/5187060
