No - the bank mortgage was used to pay off a margin loan, not to buy, build, or improve the home that it’s secured by.
For tax years 2018 through 2025, you can only deduct the interest from the amount of your loan that was used to buy, build, or improve the home that it’s secured by.
You cannot "grandfather" from the first loan, because it was not a mortgage - it was secured by stocks.
