When Imaginary Friends Go Bad

Earlier today, while I was in the kitchen, I heard my youngest howling.  My eldest was working on schoolwork at the kitchen table, so I knew she was not the cause.  Rushing down the hall, I fling open the playroom door to find my little one sobbing.  "What happened?"  I asked.  She was crying so hard that she couldn't speak.  I picked her up and asked again, "What happened?  Did you hurt yourself?"  Through her sobs she manages to utter, "Rosie hit me."  I was a little bit exasperated.  Rosie is her imaginary friend, and not a nice one at that.  I said, "You tell Rosie that she is not welcome at our house anymore."  Really.  I have enough to worry about with my two real children getting along.  I don't need to throw an imaginary one into the mix.  She seemed to perk up at my demand, and I thought maybe, just maybe, we could get rid of Rosie once and for all.  Then a couple of hours later I hear her talking to Rosie again.  I said, "I thought I told you that Rosie wasn't allowed to come over here anymore."  My youngest looks at me as though I am the dumbest person in the world.  "Mom.  That Rosie was the Rosie with ORANGE hair.  This Rosie has blue hair."  Oh.  My bad.