Yeah but she looks good for her age thou. There is a scene in our film in which the heroines are invited to pop concert and meet their idol .Their idol gives them an encouraging peep talk about hope and courage. It's quite an effective and crucial scene that is the turning point in the film.
Why not just make a "fictional" pop star in the world of the film? That way you can hire any young, attractive actress to play the part and save yourself a ton of headache. Hollywood movies do this sort of thing all the time...
If a movie needs to have Mariah Carey to make a 30 second cameo (as well as a song for the soundtrack), in order to be successful, it probably wasn't that strong of a script to begin with...