It depends. Are you filing 2023, or amending 2022?
When you start a return in TurboTax, the program asks questions in the personal info section to determine the individual's filing status including marital status.
If she filed a 2022 return as Single and it should have been Married Filing Jointly or Married Filing Separately because she was married as of 12-31-22, she would need to amend her return. If her spouse filed as Separate, they can still change to a Joint return.
If you used TurboTax Online, simply log in to your account and select “Amend a return that was filed and accepted.” If you used our CD/download product, sign back into your return and select “Amend a filed return.” You must file a separate Form 1040-X for each tax return you are amending.
See this tax tips article and this one for more information.