53 Pa. Stat. § 30579
Whenever any city establishes a retirement system under the provisions of this act, all of the assets and liabilities of any existing pension fund shall be transferred to the fund created under such retirement system.
After such transfer, the fund created under the provisions of this act shall be subject to all of the liabilities of the fund so transferred, including liability for continuing the payment of retirement allowances payable to persons retired prior to such transfer in accordance with the laws and regulations under which such persons were retired.
The moneys in the fund so transferred shall be distributed among the accounts of the fund created under the provisions of this act in such proportion as the actuary shall determine.
53 P.S. § 30579