[Nancy] went to her mother's house for a visit. Her sister [Lillian] was there as well. When [Nancy] got to the house, her mom was telling [Lillian] a story about how [Lillian]'s sibling [Nicholas] was always catching frogs and taking them into his bed.
('Nancy', 'Nicholas')
[Nancy] went to her mother's house for a visit. Her sister [Lillian] was there as well. When [Nancy] got to the house, her mom was telling [Lillian] a story about how [Lillian]'s sibling [Nicholas] was always catching frogs and taking them into his bed.
[{('Nancy', 'brother', 'Nicholas'): [('Nancy', 'sister', 'Lillian'), ('Lillian', 'brother', 'Nicholas')]}]
['sister', 'brother']