Just noticed I misspelled tracing in title (trecing). Seems I saw something in the literature recently that warned accountants to advise there clients NOT to borrow money against the equity in the homes to buy other real estate, as they will NOT be able to trace that interest. I wish I would have saved it. I will try to find and see exactly how it read and how reliable a source it came from.
However, from the 2018 Form 1040 instructions for Schedule A, I just found the following:
If you used any home mortgage
proceeds for a business or investment
purpose, interest you
paid that is allocable to those proceeds
may still be deductible as a business or
investment expense elsewhere on your
return.
So maybe there is hope.