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

1. Отец Джеймса
2.Книги его внуков
3. Имя ее сестра-в-законе
4.Фамилия Елены и Питера
5. Родители Джона
6.Брат этого мальчика
7. Дети этих женщин
8.Игрушки из близнецов
9.Музыку Глинки и Чайковского
10.Профессия этих людей
11.День рождения моего отчима
12. Она остановилась у своей тети

1. James' father
2. Grandchildren's books
3. her sister-in-law's name
4. Helen and Peter's surname
5. John's parents
6. This boy's brother
7. These women's children 
8. The twins' toys
9. Glinka and Chaikovsky's music
10. These men's profession 
11. My step-father's birthday
12. She is staying with her aunt Это не Possessive case.