Ohio Rev. Code Ann. § 1776.69
(B) Any written agreement of any merger or consolidation shall set forth all of the following:
(E)
(2) The agreement of merger or consolidation may authorize less than all of the partners of any constituent partnership, the directors of any constituent corporation, or the comparable representatives of any other constituent entity to amend the agreement of merger or consolidation at any time before the filing of the certificate of merger or consolidation, except that, after the adoption of the agreement of merger or consolidation by the partners of any constituent domestic partnership, only with the approval of all the partners may any agreement of merger or consolidation be amended to do any of the following: