I'm certainly no expert on Canadian law but I've just spent 20 minutes (using Google.ca) trying to research your question.
As I read it, the situation in Canada is exactly the same as it is in the UK. i.e. family relationships are only relevant when determining who has the right to administer the estate of a person who dies intestate. As soon as there's a will, family relationships become completely irrelevant.
In the first instance (i.e. until probate has been granted) only the executor has an automatic right to see the contents of a will. Once probate has been granted the will becomes a public document which can be seen by anyone.
Chris



