[Nancy] went out to dinner with her sister [Lillian], and [Lillian]'s daughter [April].
('Nancy', 'April')
[Nancy] went out to dinner with her sister [Lillian], and [Lillian]'s daughter [April].
[{('Nancy', 'niece', 'April'): [('Nancy', 'sister', 'Lillian'), ('Lillian', 'daughter', 'April')]}]
['sister', 'daughter']