I wouldn't think so... any additional art should conform to the game's art style, which means new zombies, child or otherwise, should have an inhuman, zombie-like appearance. I could see that argument when we get to bandits though, whom we assume will be human and look human. But 7DtD would hardly push the envelope on lifelike violence against humans, among mature games in general. It's worth remembering what that mature rating means. In the eyes of the US ratings board at least, impressionable kids aren't supposed to be playing this game.