Ohio Rev. Code Ann. § 2107.73

Persons who are necessary parties to a will contest action are as follows:

(A) Any person designated in a will to receive a testamentary disposition of real or personal property;

(B) Heirs who would take property pursuant to section 2105.06 of the Revised Code had the testator died intestate;

(C) The executor or the administrator with the will annexed;

(D) The attorney general as provided by section 109.25 of the Revised Code;

(E) Other interested parties.