1 Pa. Code § 17.92
A government member of the Joint Committee shall file in writing (Form CDL-6) with the Secretary of the Joint Committee the name of the person designated as his alternate. The designation may be changed by the governmental member or his successor in office by the filing in writing with the Secretary of the Joint Committee of the name of a different person as alternate or of a statement that the existing designation is revoked. The substitution or revocation shall take effect upon or after filing in accordance with its terms. An alternate shall take and file the oath of office prescribed by law for a public member, and shall be a member of the Joint Committee for the purposes of this part. When both a governmental member and the person designated as his alternate attend a meeting of the Joint Committee only the governmental member shall be deemed to be present for the purposes of voting and the determination of a quorum.
1 Pa. Code § 17.92