The Court may at any stage of the proceedings order that the Central Government or a State Government shall be added as a defendant in any suit involving any such question as is referred to in clause (1) of Article 132 read with Article 147, of the Constitution, if the Attorney General for India or the Advocate-General of the State, as the case may be, whether upon receipt of notice under rule 1, or otherwise, applies for such addition and the Court is satisfied that such addition is necessary or desirable for the satisfactory determination of the question of law involved.