It's a difficult one really and one that could potentially cause him problems further down the line. It would only need an over zealous parent of a friend of the child to read too much into the situation and he could find himself subject to an unwarranted multi agency investigation. It would probably be better if he gave the child some quality time and read some books to her in her own room as a settling down time and left his daughter to sleep on her own. It could inhibit the child's development by not learning age appropriate independence? How will the child manage when her friend wants her to sleep over or go on holiday with the school? Just a thought but good luck with the situation.