We've had to do the same thing - put DD in a sleeping bag as she is houdini and ends up every which way in her cot! Its usually for her late afternoon nap that it doesn't matter whether she is in a bag or not, if she gets onto her tummy she will complain until I flip her back..............just so she can flip herself over again I am still surprised at how she can still manoeuvre in her bag though - I find her every where facing any direction!! LOL!!

The bag has been great as on a hot day with aircon on it can get quite cool in her room particularly, so it keeps her comfy, not too hot, not too cold so she sleeps well.