[George] and her sister [Nancy] decided to take a trip to Mexico together. [Nancy] and her sister [Amy] played golf together. [Nancy] won easily.
('Amy', 'George')
[Nancy] and her sister [Amy] played golf together. [Nancy] won easily. [George] and her sister [Nancy] decided to take a trip to Mexico together.
[{('Amy', 'brother', 'George'): [('Amy', 'sister', 'Nancy'), ('Nancy', 'brother', 'George')]}]
['sister', 'brother']