Since NYS and NYC became your wife's domicile in April 2019, she is a part-year resident of both NYS and NYC for 2019 tax purposes. She became a resident of each as soon as she established her domicile.
NY's rule: You are a New York State part-year resident if you meet the definition of resident or nonresident for only part of the year.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
