Possessive Case in the following .
1. The father of James
2. The books of his grandcheldren
3. The name of her sister-in-law
4. The surname of Helen and Peter
5. The parents of John
6. The brother of this boy
7. The children of these women
8. The toys of the twins
9. The music of Glinka and Chaikovsky
10. The profession of these men
11. The birthday of my step-father
12. She is staying with her aunt