Imaginary friends and adoptees

About two weeks after she started school, The Girl came home and announced, "I have an invisible friend." I asked her some questions about said friend and she answered them. Not a mention since two weeks ago.

Today our daughter pretended she was a seven-year-old with the name of a baby we know (whom I happen to think is so cute and have a teeny crush -- do you ever get crushes on favorite babies? There have been a few babies who I've just fallen for). "Miley" was visiting us because her parents had gone to Africa. "Miley" stayed behind and I told her that if she wanted to stay with us forever and be The Girl's big sister, she could. "Miley" liked this idea very much and agreed to be adopted and live with us forever. "Miley" helped me paint today, saying that her little sister, whom she had decided was three, wasn't big enough to paint. I announced the addition to our family to my husband when he got home tonight.