Your daughter must file by mail. Even if your ex filed an amended return, it will not clear the e-file system to allow your daughter to e-file.
Then, if your ex does not file an amended return, both your ex and your daughter will get letters from the IRS asking them for proof of their situation. This normally happens 6 to 9 months after the April 15 deadline; I have no idea how long it will take this year. Which ever taxpayer is determined to have filed an incorrect return will owe repayment of any excess refund with interest and possibly with penalties.
