I brought them all in a big blue tupperware tub that we usually store hay in. Our cat JellyBeans watched them closely, and I watched her closely too, to make sure she wouldn't harm the babies.
I turn my back for a second, and when I turn around, I see she vanished. So I look inside the tub, and there she is, lying with the babies! She wasn't touching them or trying to eat them, simply just hanging out with them.