i had the same problem with side caring. but waant an issue unti she was crawling. she never rolled in her sleep it was just when she woke up and tried to get off the bed herself.
what is your concern? her falling out? or you/partner rolling on her? something else?
Spock would often snuggle into me and end up underneath me but because she was so snuggled in itms. but would always wake me up when she did it.