I am not sure how to connect the mortgage interest on Sch A and F. 8829.  
I think I first should enter the total mortgage interest on on the home office screen (under Indirect Expenses, Mortgage interest, without any adjustments), and then go to the Sch A screen and enter the info on the Interest - Excess Mortgage Interest -screen.  On this screen I should choose Form 2 -Business Use of Home.
Any input is appreciated