Unfortunately, the credit for the qualifying dependent is applied before the repayment of the homebuyer credit.  It is not permitted to reduce your "Other Taxes," which appear on Form 1040, Schedule 4.

If you look at Form 1040, Page 2, you can see that the credit for qualifying dependents (Line 12) is listed before the homebuyer credit repayment from Schedule 4 (Line 14) is added.