If you are the one who can rightfully claim the child because the child lived with you more than half the year and met the other qualifying child requirements, you can claim the child on your return but you will have to print and mail your return to get it accepted. They will process your return normally.
Later in the year, the IRS will request information from you and the grandparents to support each of your claims that you were the one who should have been allowed to claim the child. Whoever the IRS determines was wrong, will be required to pay back any refund received from incorrectly claiming the child along with penalties and interest.
