@LinaJ2020 Your instructions make no sense for selling a home, then buying a home.
For example, suppose the first home was sold November 1, 2020 and the second home was bought the same day.
The first mortage was 300K
The second mortage was 900K
What do you put in the box for outstanding principle? Not 1.2M. Nope.
You need to use the IRS averaging method for each loan. You put in zeros for the month where the mortgage didn't exist. That will give you two average principles. Then you can add them together.
But this is silly. Fix the calculation. It's been wrong for two years. If you need help, Tax Act has it correct.