If she did not check the box on her form 1040, that says she can be claimed as a dependent (In TurboTax, she indicates that somebody else can claim him as a dependent, at the personal information section. TT will check that box on form 1040), you can not claim her as a dependent or claim her tuition expenses, until she files an amended return, unclaiming her self.
If she agrees to amend, you do not have to actually wait for her amended return to be processed, to file and claim her. But you cannot e-file. You'll have to mail in a paper return.
Normally her refund would be the same either way, but this year there is the stimulus/rebate credit. She gets it if she does not qualify as a dependent.
Note that the requirement is not just whether she is actually claimed as a dependent, it's whether she qualifies to be claimed as a dependent.
