Is a request for leave to amend a mid-motion to a motion for summary judgment fair?

Trident submits that permitting a request for leave to amend “mid-motion” is not fair as it requires Trident to respond to an “everchanging litigation landscape.” It relies on Cosentino v. Dominaco Developments Inc., 2018 ONSC 5056, aff’d 2019 ONCA 426. In that case, the self-represented plaintiffs had brought a motion for summary judgment in what was described as a complicated and protracted proceeding. The plaintiffs then sought to further amend their statement of claim in response to the defendants’ responding record. Cross examinations had already occurred, and the defendants had already provided their answers to undertakings arising from the cross examinations. At para. 38, the court focused on the prejudice to the defendants by the plaintiffs constantly altering its pleading after the defendants had committed their position in the evidence in response to the unamended statement of claim.