How do I add more 1098 mortgage interest forms?

Yes, you may claim mortgage interest deduction regardless of the number of lenders as long as the loan does not exceed $750,000, married filing joint ($375,000, married filing separate). You may follow the steps below to enter add another 1098:

1. Login to Turbo Tax.
2. Under Federal Taxes, in Deduction and Credit tab, click "I'll choose what I work on".
3. Under " Your 2020 Deduction and Credit", click update or start next to Mortgage Interest, Refinancing, and Insurance.
4. Under " Home Loan deduction summary" click edit  and enter the lender's information, one at a time.
5. Click continue until you get to the screen " Is this loan secured by a property of yours?" 
6. Click Done.
7. The next screen is a question " Do any of the situation apply to you?".