I'm hoping this isn't too late at night to start this debate. I'm really torn between letting her stay and pushing her back to her own bed so would be interested in people's opinions on both sides.
On the one hand I do feel that humans are the only animals to push their young out at an early age and not sleep with them and that my 3 year old (and baby son who is only 7 months) get a lot of comfort and security from sleeping with us (although my 6 year old rarely comes in as she finds her father's snorning too loud ). On the other however despite having bought a queen size bed to house my brood at night my tiny 3 year old seems perfectly capable of taking up 99% of a 6ft wide bed, of insisting on removal of all covers during winter and of keeping me awake to the point where I'm struggling not to turn into bad tempered grouchy mummy. Attempts to impose any kind of control over my 3 year old's whims are met with crying which of course wakes up the 7 month old and from there its bedlam. I've spent the last 3 nights in the spare room. This wasn't my idea of family sleeping.