Not sure if there are any documents, but you could have your girlfriend look back at this thread and look at the answers people have given you that tells you WHY snakes are safe to have around kids.
Of course, you still would need to supervise the child and the snake if the child were to handle the snake. Not saying the snake would attack the child, but it's more like the child being too rough with the snake.
The snakes you own pose no threat to humans at all. Any kid could be near the snakes you own (maybe not if the snake happens to be aggressive, but that's besides the point) because the snakes are completely harmless. The snakes have no venom or rear-fangs that you own, so they do not pose a threat to the child at all.
I think it would actually be a good thing to have the snakes around the child because a ton of people say negative things about snakes to their children and to other people, spreading a rumor that isn't true (such as "all snakes are venomous"). Interacting the child and the snakes is a good thing so the child doesn't grow up in fear of snakes, but actually may want to have snakes itself. Plus, the child can learn a lot just by having snakes around it.