Oli,
I'm confused by your post: "her little friends look after her and want to be like her..." are you talking about her imaginative friends or her friends from school?
Do you have concerns that she is slipping into her made up world and not really participating in this one? Or is the just an observation where you are curious about other kids this age and how they play?
DD is all about imaginative play and spends most of her alone time doing just that, but she still plays with her friends at school. Just depending on her mood will she ask for us to participate but for the most part she can play for hours on her own creating scenes and acting them out and has done so since before age 2. I is imaginative play as a positive.
