I think you tried to use the title area to explain and that section is limited to 170 characters........ only the mortgages taken out prior to 2017 are grandfathered... look at the form on page 12 - it's pretty easy to work through and will explain what is deductible...
otherwise, please explain your details again....
https://www.irs.gov/pub/irs-pdf/p936.pdf
