S.C. Code § 9-1-450
Notwithstanding any provisions to the contrary, any teacher or employee who was a member of any other retirement plan or fund in operation on April 26, 1945 under sponsorship of any governmental agency or department shall not be entitled to membership in the System unless on or before July 1, 1946 any such teacher or employee indicated by a notice filed with the Board on a form prescribed by the Board his individual election and choice to participate in the System. If a majority of the members of any such retirement plan or fund so voted all members of that retirement plan or fund became eligible to participate in the System and became members of the System unless within thirty days next succeeding a date named by the Board they elected not to become members.
S.C. Code § 9-1-450