In response to number three: In Ontario, a common-law spouse does not, at this time, automatically have the same property rights as a married spouse - so if they just recently moved in together (even if she's pregnant), she would have problems making a property claim (if she has been his common-law for a while, she can make different claims which I won't go into here). On the other hand, it might be possible for her to make some sort of support claim.
The child, on the other hand, would be a legal heir.
Of course, all of this depends on whether the man has a will. A will will automatically become invalid on the date of a marriage, but it doesn't become invalid if two people start living together. On the other hand, wills can be challenged if someone who should be included isn't (again, I wouldn't go into all those rules here).
Having said all that, keep in mind that if you are writing an L and C fic, they are living in the state of New Troy, so you can probably make up your own laws.
