You do not enter her 1098-T on your tax return (since she is not your dependent).
Grad students are not eligible for the refundable American Opportunity Credit (AOC).*
The only credit available to grad students is the Lifetime Learning Credit (LLC). It is a non refundable credit. That is, it can only be used to offset an actual tax liability (no refund). So she may be able to claim the 1098-T on her tax return.
*The more generous and partially refundable American Opportunity credit (AOC) is available for graduate education in the same year that you completed your bachelors degree.
