I have 3 sleeping in the same room and I find they sleep better. I tell them " no talking " before I leave and I rarely have an issue. I also find that if one is asleep and another starts to fuss or cry even, the first one rarely wakes up.

I think if you are consistent, they'll get it. I don't allow toys or books. I allow one stuffy or sleep blanket if they want to bring one from home. In my mind, a toy or sleep blanket gives the idea that play is aloud.

If they wake each other up, too bad... they will be sleepy, but still keep them where they are for the full 2 hours.

I don't allow children to stop napping until the summer before they attend school.