Lila's Little Sister

Ellie McMillan, a little girl from the day-care center where the Unicorn Club volunteers, has run away from home--to my house!  I know, you're thinking Lila Fowler and kids go together like grape juice and white carpet, but--believe it or not--I actually enjoy reading and playing hide-and-seek with Ellie.  It's almost like having a little sister.  The only problem is, she wants to move in permanently!  You see, Ellie's mom just started going out with a new guy, so Ellie's been spending a lot of time with me.  I guess she figures if her mom has a boyfriend, she doesn't need Ellie anymore.  I promised Ellie I wouldn't tell any grown-ups that she's at my house.  But Jessica and the other Unicorns say Ellie has to go, promise or no promise.  Is there a way to keep my word and get Ellie back where she belongs?