How do I add Form 1040 Schedule 1 to my return?

A Schedule 1 would be included in your tax return if the tax data being entered required the Schedule 1.

I have a similar situation. I need to add additional income of less than $400. I wasn't required to receive a1099-MISC due to the amount.

Yes, you can add additional income to your return as 'Other income' using the steps below based on your situation.

Other Miscellaneous Income:

1. Sign into your TurboTax Online account
2. Go to Tax Home (left panel)  Wages and Income  section
3. Scroll to  Less Common Income > Select  Miscellaneous Income, 1099-A, 1099-C
4. Select Other reportable Income > Enter a description (----) and the amount