What factors will be considered to support a finding of special circumstances in a motion to add a defendant to the list of defendants?

The fact that the proposed defendant has already been involved in some manner as a party in the subject or related proceedings, will also be a factor tending to support a finding of special circumstances. Further, the relative disadvantage to a party being added compared to the disadvantage to the plaintiff if he is not added must be weighed. As noted by Molloy J. in Robertson v. O’Rourke, [1997] O.J. No. 3724, this principle, although not expressly spelled out, underlies many of the cases in this area. For example, courts sometimes refer to the fact that the plaintiff may have no other source of recovery or to the reverse situation, that the plaintiff will still have full recourse against other parties.