Uniform Civil Procedure Rules 1999

A plaintiff or applicant may, whether seeking relief in the same or different capacities, include in the same proceeding as many causes of action as the plaintiff has against a defendant or the applicant has against a respondent.

However, causes of action may be included in the same proceeding only if at least 1 of the following conditions is satisfied—

if a separate proceeding were brought for each cause of action—a common question of law or fact may arise in all the proceedings;

all rights to relief sought in the proceeding (whether joint, several or alternative) are in relation to, or arise out of, the same transaction or event or series of transactions or events;

the court gives leave, either before or after the start of the proceeding.