Based on your question, you have two sons in high school. The son who does not have a 1099-Q does not get any tax benefits and you should delete their entries completely.
There are certain tax benefits for higher education (college and above) including the Lifetime Learning Credit, the American Opportunity Tax Credit, and the Tuition and Fees Deduction (for which 2020 is the last year). These are only available for higher education.
529 and other plans were originally created to pay higher education expenses, but Congress expanded them to cover K-12 expenses. They also cover a more generous list of expenses than the higher education tax credits, up to $10,000 per year.
https://www.irs.gov/taxtopics/tc313
If your children are not in college, there are no federal tax benefits, except the ability to reimburse expenses from a 529 plan. If you did not use a 529 plan for one of your sons, there are no tax benefit's for that son's education.
