Your future son-in-laws parent's explanation about what their insurance agent has said sounds legit. Many insurance companies will not insure a car that is garaged outside of the state of the insurance policy and is not in possession of the registered owner. There are some exceptions, such as when a child is away at college with a parent owned car which would not apply here since he has now graduated.

As for your daughter's fiance obtaining insurance, there are insurance companies that will allow you to place insurance on a car that you do not own or have insurable interest. Esurance is one such insurance carrier.

If he cannot find insurance on his own though he should see about his mom adding him to the title and then registering and insuring the car himself in Ohio.

For an Ohio auto insurance quote follow this link.