Yes, a grandparent has the right to intervene in the divorce case, or file a separate case, seeking visitation. A grandparent also has the right to seek custody, but has the additional burden of proving that the parents are not fit to have custody. You need an experienced custody/grandparent rights attorney who regularly handles such cases in the county where the parents live.
I am exclusively a family law attorney, practicing primarily in the metro Atlanta, Georgia trial courts. However, I handle appeals from anywhere in Georgia.