[Theresa] took her son [Nicolas] to [Lillian] ([Theresa]'s sister) birthday party.
('Lillian', 'Nicolas')
[Theresa] took her son [Nicolas] to [Lillian] ([Theresa]'s sister) birthday party.
[{('Lillian', 'nephew', 'Nicolas'): [('Lillian', 'sister', 'Theresa'), ('Theresa', 'son', 'Nicolas')]}]
['sister', 'son']