maybe he should be forced to play with a grizzly bear for a while!!
All of you have some really good ideas, but Steves has got the right idea! You are not in the wrong, tell him how it is and do everything you can to protect your grandkids.
PLease smack him firstfour having freaking rats as pets, and second for making the rats and the cats play together. This sounds like a recipe for the kids to get hurt if the rats and cat start fighting, and for them to be heartbroken when the inevitable happens.
Unfortunately, you are correct Dinosaur. It's a shame that adults don't act responsibly and teach their kids about animal behavior. It's really stupid to expect cats and rats to get along. It's also incredibly stupid to expect ANY wild animal to act like anything but what it is-a wild animal. They can turn on a dime. I find it especially disturbing when all of these wildlife "experts" live with the animal. It just encourages reckless behavior from those who are a few bricks shy of a load.