What is the standard of review of an order of a master refusing to allow a party to be added?

The order of the master refusing to allow a party to be added was a final order. The other aspects of his order were interlocutory. On appeal, the decision of a master is entitled to the same level of deference with respect to findings of fact and the exercise of discretion as would be accorded to the decision of a judge. The standard of review of an order, whether final or interlocutory, is correctness with respect to questions of law. Where the master exercises discretion, the court on appeal must determine whether the correct principles were applied and whether the master misapprehended the evidence such that there is a palpable and overriding error (see Zeitoun v. The Economical Insurance Group (2008), 2008 CanLII 20996 (ON SCDC), 91 O.R. (3d) 131 (Div. Ct.)) aff’d 2009 ONCA 415 (CanLII)). Background facts