For the person on the 1098, enter the 50% as mortgage interest paid to a financial institution.

For the person NOT on the 1098, enter in the next slot, there is a 3 vertical dots to add that information for the 1098 it is being generated from and formatted to match the IRS instructions for Schedule A. 

Thank you!  But it's not allowing me to enter the info required.  I need to enter the mortgage interest in the business use of home deduction worksheet and that does not allow me to enter the info- so I'm looking for a place to enter supplemental information to generate a supplemental statement.  Does anyone know how to do this?

TYIA!!

As much as it would be nice to do so, that feature is not available. Simply enter as Mortgage Interest. In the description, include your notation. It will not go with the return. You can then adjust Schedule A, with annotation, if necessary.
If you really want this, change to Lacerte.

You could create a pdf attachment.