When Cousins are "Frenemies"

Whenever my Youngest and his cousin, let's call him Jake, come into contact, you can almost hear the theme from "The Good, the Bad and the Ugly" waft through the air.  Their relationship is fairly well characterized by a recent exchange: I corrected Youngest, asking him not to obliterate his sister's toy; Jake helped me out by reinforcing my statement; youngest plonked him in the head with a whiffle ball.

My first thought was "hey, good arm," my second was "wife's closer, not it," my third was "did my brother-in-law see that?"

My brother-in-law had indeed seen it, and, no, he didn’t retaliate upside my head with the queso dish.  Fortunately, we get along much better then our kids do.  And we’re in agreement that we're not giving in.  These boys are cousins and they are going to spend time with each other.  They want to play it North Korea, South Korea, fine.  As long as open hostilities don't break out, we're good.

And there are a few blissful moments when the boys engage and actually play nice.  On the beach yesterday the two joined in a public works project until things broke down over union regs – who was supervisor and who was day labor.  There was a sit-down strike.  Negotiations collapsed.  Then the sandcastle.

My brother-in-law and I both know that the small difference in the boys' ages will soon disappear, and they'll be sneaking off to Lighthouse beach to split a twelve-pack.  Until then, we'll just try to keep a sense of humor about the whole "frenemies" thing.

At least our daughters get along.  Mostly.

So how do you deal with it when your kid doesn't get along with the kids of close friends or relatives?  Has this ever caused you problems?