[Glen] and his father [Nicholas] went to the zoo. [Nicholas]'s sister [Lillian] was supposed to come with them, but could n't.
('Glen', 'Lillian')
[Glen] and his father [Nicholas] went to the zoo. [Nicholas]'s sister [Lillian] was supposed to come with them, but could n't.
[{('Glen', 'aunt', 'Lillian'): [('Glen', 'father', 'Nicholas'), ('Nicholas', 'sister', 'Lillian')]}]
['father', 'sister']