If there's one thing in this world that's older than jokes about your spouse, it's jokes about your spouse's mother.
And unfortunately, there are no shortage of mothers-in-law that live down to this unpleasant reputation of being overbearing about the way their grandchildren are being raised or just not respecting boundaries in general. But at the same time, there are just as many who are happy to treat the new members of a family as if they'd been there all along.
So sometimes, it doesn't have anything to do with a mother-in-law's actual behavior when a family argues about her. As the thorny issue we're about to look into illustrates, sometimes the biggest fights are about a complicated situation that's beyond her control.