(1) Any person interested in a suit between other parties may in- tervene therein at any time before judgment. (2) The intervention shall be made by the filing of a separate sta- tement containing all the grounds which justify such person in intervening. (3) Where the intervention is allowed, the proceedings shall be stayed until the parties have been served with a copy of the statement of the intervening party. (4) Where service is not effected for a reason attributable to the intervening party, he shall be deemed to have withdrawn his statement. (5) Nothing in this Article shall affect the provisions of Arts. 293-299.