The decision in Corp. of Township of North Shore v. Grant has a helpful summary of misnomer principles:
[18] Nonetheless, motions to correct misnomer or misdescription are still permitted pursuant to s. 21 of the Limitations Act, 2002, which provides:
(1) If a limitation period in respect of a claim against the person has expired, the claim shall not be pursued by adding the person as a party to any existing proceeding.
(2) Subsection (1) does not prevent the correction of a misnaming or misdescription of a party.
[19] Section 21 has been held to apply equally to motions in which a plaintiff seeks to substitute a plaintiff in an action, notwithstanding language that appears to refer only to defendants being substituted: Horgan v. Tanktek Environmental Services Ltd. (2009), 178 A.C.W.S. (3d) 87 (Ont. S.C.), aff’d 2009 ONCA 820 (CanLII).
[20] There is a debate in the jurisprudence as to whether a request to amend a pleading by adding a party who was omitted altogether from the style of cause is properly characterized as a request to correct a misnomer or misdescription. Some cases have held that it is not and, instead, have allowed the amendment using the court’s power to cure a “technical irregularity”: see Hastings v. Halton Condo Corp. to 324 et al., 2012 ONSC 175 (CanLII); Toronto Standard Condominium Corporation No. 810 v. King Spadina Development Corporation, 2014 ONSC 5560 (CanLII), 2014 ONSC 5560 (Master).
[21] Regardless of the manner in which a request to substitute a plaintiff is characterized, the jurisprudence is clear that an amendment will be permitted where there is a “coincidence” between a plaintiff’s intention to sue and the intended defendant’s knowledge of the plaintiff’s intention. In Lloyd v. Clark, 2008 ONCA 343 (CanLII), the plaintiff was denied leave by the motion judge to name the Regional Municipality of Durham as a defendant in place of the Town of Ajax and the Corporation of the Town of Whitby. In a brief endorsement allowing the appeal, the Court of Appeal held:
The case law amply supports the proposition that where there is a coincidence between the plaintiff’s intention to name a party and the intended party’s knowledge that it was the intended defendant, an amendment may be made despite the passage of the limitation period to correct the misdescription or misnomer. [Citations omitted.]
[22] Although Lloyd was a case in which a plaintiff sought to substitute a defendant, it has frequently been applied in cases in which a plaintiff seeks to substitute or add a plaintiff: see, for e.g., Streamline Foods Ltd. v. Jantz Canada Corp., 2010 ONSC 6393 (CanLII), aff’d 2011 ONSC 1630 (CanLII), 2011 ONSC 1630 (Div. Ct.), 2012 ONCA 174; Tetreault v. Nussbaum, 2015 ONSC 6226 (CanLII); Asset Strategy Corp. v. Rodinia Lithium Inc., 2016 ONSC 5337 (CanLII) .
[23] Thus, an amendment to add the name of one or more plaintiffs to a statement of claim should be permitted notwithstanding the expiry of a limitation period where the court is satisfied that the plaintiffs sought to be added to an action were intended plaintiffs prior to the expiration of the limitation period, that the defendant knew that they were intended plaintiffs, and where no prejudice arises that cannot be compensated for in costs.
[24] I am satisfied that this is the situation here. There is ample evidence in this case both of the intentions of the Council Members to claim against the defendant and of the defendant’s knowledge of those intentions.