20 Pa.C.S. § 4503

The surety of a fiduciary may intervene in any proceeding which may affect the liability of the fiduciary and shall have the right to except to and appeal from any action which may affect the fiduciary's liability. When the court has finally determined the liability of the fiduciary, the surety shall not be permitted thereafter to deny such liability in any proceeding to determine or enforce his individual liability, whether or not he received notice of the proceedings which established the liability of the fiduciary.