You never enter or report the advance Child Tax Credit anyone else got. If you claim her and the child you might get the full Child Tax Credit on your return. She might have to file her return as a dependent and might need to pay the child credit back.
You can only claim her if she lived with you the whole year and had less than $4,300 total income.
Who can I claim as a dependent?
https://ttlc.intuit.com/community/credits-and-deductions/help/who-can-i-claim-as-my-dependent/00/267...
