Ohio Rev. Code § 2105.15
A person of sound mind and memory may appear before the probate judge of the person's county and in the presence of the judge and two disinterested persons of that person's acquaintance, file a written declaration declaring that, as the person's free and voluntary act, the person did designate and appoint another, stating the name and place of residence of the other person specifically, to stand toward the person in the relation of an heir at law in the event of the person's death. The declaration shall be attested by the two disinterested persons and subscribed by the declarant. If satisfied that the declarant is of sound mind and memory and free from restraint, the judge shall enter that fact upon the judge's journal and make a complete record of the proceedings. From then on the person designated will stand in the same relation, for all purposes, to the declarant as the person designated could if a child born in lawful wedlock. The rules of inheritance will be the same between the person designated and the relations by blood of the declarant, as if so born. A certified copy of the record will be prima-facie evidence of the fact stated in the record, and conclusive evidence, unless impeached for actual fraud or undue influence. After a lapse of one year from the date of the designation, the declarant may have the designation vacated or changed by filing in that probate court an application to vacate or change the designation of heir; provided that there is compliance with the procedure, conditions, and prerequisites required in the making of the original declaration.
R.C. § 2105.15