Little Darlings by Jacqueline Wilson
Ex-library book, kindly donated. Worn on the cover, stickered up on the spine, but otherwise perfectly readable
 
Sunset lives a life of luxury. Her mum is a beautiful ex-model, her dad is a world-famous rock star and her little siblings are celebrities! But life on the red carpet is no compensation for arguing parents, media scrutiny, and having no real friends.

Destiny, on the other hand, lives on a rundown estate. She's an only child with a sickly but devoted mum who constantly tells her she's the daughter of a famous Rockstar.

When the two girls meet in unlikely circumstances, they find in each other something they've been missing all their lives.