Enter all your business income, including 1099-NEC forms, in the business section.
If you entered the 1099-NEC in the personal section of the program and checked "I have expenses for this income" that will create a schedule C. But I don't know if it will link to the existing schedule C, or if it will try and create a new schedule C for a separate business. Turbotax really changed how 1099s were entered this year and there seems to be a high likelihood that people can enter a 1099-NEC and not create a proper schedule C or pay SE tax, which will cause big headaches for those taxpayers down the road.
I know that if you enter one 1099-NEC and check the box for "I have expenses" it will create a schedule C. I haven't done any testing to see what happens if you enter another -- does it create a new Schedule C or go on the first one? But the safest thing to do is only use the business section to enter business income. And print your return and review it carefully before filing.
