Did she make a mistake in MY INFO and say that no one could claim her? You have to go to MY INFO, click her name and go back through the questions for the one that asks if someone else can claim her as a dependent and say YES.
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-a...
Do not expect quick results from amending. It can take four months or more for the IRS to process an amended return.
You can watch for information here:
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**