“(1) The Tribunal may give a direction adding, substituting or removing a party as an appellant or a respondent. (2) If the Tribunal gives a direction under paragraph (1) it may give such consequential directions as it considers appropriate. (3) Any person who is not a party may apply to the Tribunal to be added or substituted as a party. (4) If a person who is entitled to be a party to proceedings by virtue of another enactment applies to be added as a party, and any conditions applicable to that entitlement have been satisfied, the Tribunal must give a direction adding that person as a respondent or, if appropriate, as an appellant.”