The Seven Sisters Series By Lucinda RIley

This series focuses on the adopted daughters of a mysterious millionaire they call Pa Salt. After the death of their adoptive father, Maia and her sisters gather together at their family mansion in Geneva where each sister is handed a clue about their natural parents.

This series includes: 

1. The Seven Sisters
2. The Storm Sister
   
3. The Shadow Sister
4. The Pearl Sister
5. The Moon Sister
6. The Sun Sister
7. The Missing Sister
8. Atlas: The Story of Pa Salt