[Robert] and his brother [Kevin] got into a fight over who was the better basketball player. [Robert] and his sister [Heidi] went to the movies to watch the newest superhero flick.
('Kevin', 'Heidi')
[Robert] and his brother [Kevin] got into a fight over who was the better basketball player. [Robert] and his sister [Heidi] went to the movies to watch the newest superhero flick.
[{('Kevin', 'sister', 'Heidi'): [('Kevin', 'brother', 'Robert'), ('Robert', 'sister', 'Heidi')]}]
['brother', 'sister']