30. The Court or Judge may at any stage of the proceedings and either with or without an application for that purpose, being made by any party or person and upon such terms as shall seem just, order that the name or names of any party or parties be struck out or that the names of any person or persons who are interested in the action or who ought to have been joined either as Plaintiffs or Defendants or whose presence before the Court is necessary in order to enable the Court effectually and completely to adjudicate upon and settle all questions involved in the action be added.