Useful co-sleeping tip #7: Don't be afraid to kick them out.
We have a toddler bed next to our bed (on my side) for our three year old to sleep in. Although she has spent all night in her own bed for about one and a half years, she has recently wanted more snuggle time in the early morning and has been asking to come into bed. I let her in as long as she promises to stay still. At the first motion that disturbs my return to sleep, I put her back in her bed. It has worked very well. She let me know recently that she crosses her legs to help her stay still. I can't imagine sleeping with my legs crossed but I'm thankful she has discovered her own way to obey.