16 Pa. Stat. § 1620
The salaries and compensation of county officers shall be as now or hereafter fixed by law. The salaries and compensation of all appointed officers and employes who are paid from the county treasury shall be fixed by the salary board created by this act for such purposes: Provided, however, That with respect to representation proceedings before the Pennsylvania Labor Relations Board or collective bargaining negotiations involving any or all employes paid from the county treasury, the board of county commissioners shall have the sole power and responsibility to represent judges of the court of common pleas, the county and all elected or appointed county officers having any employment powers over the affected employes. The exercise of such responsibilities by the county commissioners shall in no way affect the hiring, discharging and supervising rights and obligations with respect to such employes as may be vested in the judges or other county officers.
16 P.S. § 1620