The ABCA has upheld an ABQB decision to stay proceedings by a 3rd party pending arbitration between others. See Yaworski v Gowlings, 2013 ABCA 21.
The court can do this when it is just and equitable . “…arbitrations cannot be avoided by simply having a related party commence a lawsuit claiming relief with respect to arbitrable subject matter.” The appeal court noted “the arbitration between Gowlings and Yaworski PC may give the appellant (through his PC) everything or practically everything he seeks in his statement of claim. In these circumstances, it is just to stay the appellant’s statement of claim in order to avoid the cost of parallel proceedings.”