[Lillian] asked her sister [Nancy] if she could come over for dinner. [Nancy] told her she could n't, because she had to care for her sick son, [Kevin].
('Lillian', 'Kevin')
[Lillian] asked her sister [Nancy] if she could come over for dinner. [Nancy] told her she could n't, because she had to care for her sick son, [Kevin].
[{('Lillian', 'nephew', 'Kevin'): [('Lillian', 'sister', 'Nancy'), ('Nancy', 'son', 'Kevin')]}]
['sister', 'son']