A guardian ad litem may be appointed at the request of either party or upon order of the Court. Any guardian ad litem appointed under this rule shall be certified by the Guardian ad Litem Certification Board. The Court shall apportion payment between the parties. Written reports of the guardian ad litem shall be kept in an envelope marked confidential within the court file, and shall only be disclosed to parties or attorneys to the action. Absent good cause shown, a guardian ad litem shall not be appointed while the parties are engaged in mediation.