You can Add a Third State.
- Click on "State" located in your Menu Bar located on the left-hand side of your screen
- Click "Continue"
- On the next screen, you should see the state(s) you already have, click "Add Another State"
- From the drop-down choose the third state you want to add
See Images Below
TurboTax FAQ - How do I file a part-year state return?
