Amy has just learnt to roll on her belly which is great but...

We can't keep her in her cot. As soon as we put her in the cot she rolls on her side or rolls over completely and we find her with her leg through the bars on the cot face down. She is able to get her arms forward and lift her head with no problems but she has not learnt to roll from her back to tummy yet. She is always in a Grobag. She can't actually get out of the cot but we hate seeing her with her arms or legs hanging out.

Any suggestions on how to keep her in one place? We were thinking of putting some plywood around the edges and don't want to use material cot bumpers because of SIDS. We have an anti-roll pillow but SIDS don't recommend it either.

Thanks in advance.