This is the simple method:
Enter the 2nd school 1098-T, on your return, with $4000 in box 1 and box 5 blank.
Enter the 2nd school 1098-T, on his return, with $0 in box 1 and $13,040* in box 5. Enter no other numbers.
Ignore the $660 1098-T.
*26,400 - 16,700 -660 + 4000 = 13,040 Taxable scholarship will be reported on his tax return (in addition to the $6300 W-2). 13,040 + 6300 = $19,340 reportable income - 14,600 Standard deduction = $4740 taxable income; about $570 in tax ($480 of which gets you the $2500 AOTC, on your return).
If you have some book and a computer expenses, you can reduce the $13,040 amount (going in his box5) by those costs.
