My sister has co slept with her 10. Month old DS and has been trying for a while to get him to sleep in his crib. He is starting to stand up in his crib and gets really upset when we put him back onto his back. He freaks out with the pu/pd method. And he thinks it's all a game until he gets cranky. she nurses him to sleep for naps and bedtime and really wants to transition him to sleeping on his own. What do you do in this situation? Thanks all!