Yes, essentially you are running into the same situation. The finalized worksheet to correctly calculate the mortgage interest deduction when there are more than one mortgage and the total outstanding principal exceeds $750,000 will be available on February 17, 2022.
If your HELOC is fully deductible, TurboTax will automatically calculate your average balance on both loans and give you the mortgage interest deduction based on that. Make sure you properly enter the mortgage origination date as that sounds like it will make a large difference in your case.
@cfelbab
