The more I read the threads to this the more upset I got. An objection filed within 21 days I thought was the first step. It was stated several times that the "father" did not exercise his visitation rights so if the mother has not allowed the child to go over to the grandparents house what is she in violation of? Does your order state that you have to provide the transportation for the "fathers" visits also? If not, then does he just not show up when it's time for his weekends? From my own experience only, don't ever think that a Grandparent wouldn't put there grandchild in a harmful situation because it does happen! Why? Who knows why they would defend there child who is doing wrong instead of protecting their grandchild who is young and doesn't know certain behavior is wrong. The only thing they are teaching there child is how "not" to be responsible for there own actions. Most people would have the common sense to use "tough love" but there are some that don't.
If my opinion counts for anything, I think your doing the right thing, file an objection, protect your very young daughter. Does Ohio have Friend of the Court?