16 Pa. C.S. § 14720
The salaries and compensation of county officers shall be as provided under law. The salaries and compensation of all appointed officers and employees who are paid from the county treasury shall be fixed by the salary board established under section 14722 (relating to salary boards). The board of county commissioners shall have the sole power and responsibility to represent judges of the court of common pleas in proceedings before the Pennsylvania Labor Relations Board or collective bargaining negotiations involving employees paid from the county treasury, the county and all elected or appointed county officers having employment powers over the affected employees. The powers authorized by the county commissioners under this section shall not affect the hiring, discharging and supervising rights and obligations with respect to employees as may be vested in the judges or other county officers.
16 Pa.C.S. § 14720