No person elected or appointed sheriff, or any elected or appointed Marengo County official, may assume a supernumerary office after the effective date of this amendment. Any person who, on the effective date of this amendment, is entitled to participate in a supernumerary program may continue to participate in that supernumerary program, which shall include the assumption of a supernumerary office according to the terms and conditions of the law which established that supernumerary program. Every sheriff and elected or appointed Marengo County official may participate in the Employees' Retirement System of Alabama upon the same terms and conditions as may be specified by law for any other employee in the same retirement system. Marengo County officials holding office at the time of the ratification of this amendment shall be eligible to purchase service credit in the Employees' Retirement System for the time the official has served in the current office; provided, however, the official shall forego the assumption of a supernumerary office. For the purposes of this amendment, the words "elected or appointed county official" shall include any person appointed to serve the remaining term of an elected or appointed official, but shall not include a judge, district attorney, legislator, constable, school board member, or any official elected from a judicial circuit.