No elected or appointed Blount 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 elected or appointed Blount County official may participate in the Employees' Retirement System upon the same terms and conditions as may be specified by law for any other employee in the same retirement system; provided, the official shall forego the assumption of a supernumerary office. Blount 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, that costs associated with the purchase of prior service credit as prescribed in Section 36-27-6.1, shall be the responsibility of the official making the purchase. 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 county official, but shall not include a judge, district attorney, legislator, constable, school board member, or any official elected from a judicial circuit.