K: My sister is going to come over later.

Me: You have a sister? Where?

K: She’s somewhere else. Someone else has her.

Me: Really? What’s she like?

K: Pink and whitey and squiggly. Her name is Treetui.  My brother is coming over too.

Me: Wow! You have a brother too? Where’s he?

K:  He lives in another house. He’ll come over and play here because I’m too happy to go over and play in his house. I’m going to live with John and my little sister and brother will come over here tomorrow.

Me: I see. So John’s going to take care of this, is he?

K: Yes. He will bring my little sister over here and my little brother can play with my Lego sometimes too.

Me: So I don’t have to do anything about this little sister at all?

K: No. She’s just like Tamar (note: Tamar is my sister) only lots smaller and she has her own bear too.

Me: Do your sister and brother live in the same place?

K: Yes. They are too tired to come over tonight and tomorrow my sister will come over, but my brother will be too tired to go in the woods. My little sister said at her house, “but I want to go to Katherine’s” and I said “of course, but you have to put your shoes on.”
Me: You definitely have an amazing imagination.

K: Yeah. I have a really good imagination of my stories in my head.

Me: So these are a pretend sister and brother?

K: Yes, but I could play with my cousins instead. Right?

Me: Yep. They’re real enough….

Note to those who aren’t in the know: She doesn’t have a sister or a brother and (with luck and good management) probably never will. That may be why she idealises the concept. A real sibling would set her straight soon enough.