Review your return carefully to be sure you didn't claim something on him*. The TT interview is designed for divorced parents when the mom lets the dad claim the child. The mom can still claim some things. Those special rules don't apply when the mom is letting the grandparent claim the child. You can not claim anything. It's best to not enter the child at all. You may still have to amend.
*Earned Income Credit, day care credit or Head of Household filing status, even the child tax credit.
