Can a dependant's support claim against an estate freeze the sale of estate property in Ontario?

Yes, potentially. Under Ontario's Succession Law Reform Act, a person who qualifies as a dependant of the deceased can apply to the court for support from the estate if they were not adequately provided for. Because this kind of claim can affect how much of the estate is available and to whom, the court has the power to make interim orders while the application is pending, which can include restricting the estate trustee from distributing assets, and in some situations affecting whether or how specific property can be dealt with, until the support claim is resolved.

This doesn't necessarily mean a property sale itself is automatically blocked outright — selling a property and converting it to cash proceeds can sometimes still make sense for the estate — but it generally does mean the trustee needs to be cautious about finalizing distributions or otherwise dealing with the estate in a way that would undermine a pending or reasonably anticipated dependant support claim. An estate trustee aware of a potential dependant claim, or a dependant considering one, should get legal advice promptly, since the specific effect on a pending sale depends on the timing and nature of the claim.