@Rick19744 , my understanding is that even the regular monthly payment first pay off the debt on primary. Only when entire 750K on primary is paid off (regardless of whether you do it by just the regular monthly payments or do lump sum payments every now and then in addition to regular monthly payments), you start paying the debt on ADU.
I didn't see any thing in debt repayment ordering rule which said that it applies only for payments which are __not__ the regular monthly payments.
