It's still not clear.
You say "even though she can be claimed as a dependent, she is doing her own taxes (that's what we want). She will not be a dependent on our taxes. On her taxes, she did check that no one can claim her as a dependent.
That's wrong. If she "she can be claimed as a dependent", she must check that someone can claim her. She can still file her own return, but she must check that box that "Someone can claim :: You as a dependent".
It's also not clear what you are trying to gain by having her claim herself. You may be losing the $500 "Other Dependent Credit", unless your AGI is over $400K (Married filing jointly).
It's not kosher, but so far your haven't described anything that would require an amended return.
With the tax law change, effective 2018, most student-dependents will get the same refund whether they claim themselves or not. The personal exemption has been eliminated and the standard deduction increased. But, if they have more than $1150 of unearned income, that's not true.
