How do I enter 1098-Ts for three kids in college

If there is information for a student that carries over from last year, it will often start by asking all of the questions for this child first, and then at the very end of the education section allow you to add the information from forms. 

If after getting to the very end of the section you still cannot add them all, try this solution to delete the placeholder from last year, and reset the entire section:

1. Click on Tax Tools in the menu on the left of the screen.
2. Click on Tools.
3. Scroll down the list of forms and click delete beside Form 1098-T.
4. Confirm on the next screen by clicking Delete Form.
5. Scroll down the list of forms again and click Delete beside Education Tuition and Fees Summary.
6. Again, confirm on the next screen by clicking Delete Form.

This should clear the section out entirely and let you start fresh.