Fun/creative ways to tell a teen she's being placed with us? I'm looking for ideas on how to tell a 16 year old girl that my spouse and I are going to be her foster parents.

For background, I have been volunteering through a local non-profit as her mentor for the past 2 years and we have developed an amazing relationship.  She's been in foster care since she was 8 and her parents' rights were terminated a long time ago.  She's been asking to come live with us for almost a year, but we haven't been ready until now.   I'd like to come up with a fun and creative way to tell her she's going to be placed with us this summer.  She loves reading, Harry Potter, and animals, if that helps.  Any ideas?