The above notwithstanding,  the following shall apply in connection with appeals filed by a party entitled to  appeal but which was not a party to the proceedings that led to the decision  being appealed:   (a) Within fifteen days from notice of the decision, such party/ies  shall have the right to request a copy of the case file from the  body that issued the decision;   (b) If such a request is made within the fifteen -day period, then the  party making such request shall have twenty -one days from  receipt of the case file to file an appeal to CAS .