Keep your cats in your room when you are not home. I would be terrified of leaving them out with a baby, under anyone's supervision.

Find different accommodation. I'm going to sound like an asshole here but at a glance I haven't seen anyone raise the following issue: Thanks to your cats, they have the responsibility of not only watching their baby but also watching your cats around their baby. Your housemates may have agreed to having two cats around their baby, but it's simply not always a smart idea. That's their fault for accepting, not yours.

You see, living with a couple is bad enough. Add a baby in for stress, some bad young parenting AND your cats...we know who's going to end up being blamed for everything that goes wrong between them, that person is you. And it's going to start with you complaining to Amy about Aiden. I get that you're concerned about the way Aiden watches the child, but that's a whole different issue, and something you should speak to Amy about after you have moved out, if you still want to.

I hesitate to say this but the comments about how the scratches may not even be from your cats, etc., are in my opinion completely unhelpful. We've all read stories about people's cat(s) and infant(s) getting along well. It doesn't contribute anything to your situation here. I've had a cat for over 10 years. Just a week ago she scratched me in my face, right underneath my eye, completely unannounced, for the first time ever. Does that information change how you view your own cats? It shouldn't, and neither should other people's anecdotes. You don't want your cats hurting the baby, and you don't want them blamed for stuff they may not have done, so pop those lovely assholes in your room while you're not around and move the hell out.