Deductions & credits

If the prepaid interest is not included in the 1098s, you can enter the 1098 and check the box for "the amount of interest I am claiming is different than on the 1098".  Enter the total amount (in other words, for lender A, add the amount prepaid to lender A to the regular interest included in the 1098; do the same separately for lender B, etc.)  You will be given a space to write an explanation.  Keep it simple.  Keep your proof in case the IRS sends a letter asking for more information.