—(1) Subject to Rule 5(1), a plaintiff may in one action claim relief against the same defendant in respect of more than one cause of action —
if the plaintiff claims, and the defendant is alleged to be liable, in the same capacity in respect of all the causes of action;
if the plaintiff claims or the defendant is alleged to be liable in the capacity of executor or administrator of an estate in respect of one or more of the causes of action and in his personal capacity but with reference to the same estate in respect of all the others; or
with the leave of the Court.
(2) An application for leave under this Rule must be made by ex parte summons supported by affidavit before the issue of the writ or originating summons, as the case may be, and the affidavit must state the grounds of the application.