Ontario is a jurisdiction where there is broad testamentary freedom. What that means is that, beyond some basic rules, you can leave your estate wherever you want. If you are legally married (not common law), you have to consider your spouse’s rights. If you have minor or dependent children, you have to consider their rights. And if you financially support someone, even if they are not related to you, they may also have a claim on your estate. Beyond that, you can leave whatever to whoever.
Leaving your estate to one niece and not the other? Totally fine. Cutting out adult, independent children and leaving everything to charity? A-OK. You are always best to consult a lawyer before making a decision that could be controversial, especially if the beneficiaries will need to get along with people who were cut out, but you have no legal obligation to leave an inheritance to someone who doesn’t have a clear right to it.
