In most cases there is no need to file an amended return if the amended return does not show any change. But it in this case there will be a change in the amount of income and the AGI, even though the amount of tax doesn't change. Also, if their 2023 tax return has a capital loss carryover from 2022, but their 2022 tax return does not show a capital loss, the IRS will probably disallow the carryover because on the 2022 tax return there is no loss to be carried over. It's very easy for the IRS to check, and they probably check it routinely, without doing an actual audit.
For those reasons, I think you have to file an amended return, and attach the new Schedule D and Form 8949 to the amended return. If you e-file the amended return, TurboTax will include the necessary forms.
