[Nicholas] liked to talk about his sister, [Lillian]. [Clarence] took his son [Nicholas] to school this morning because he missed the bus.
('Clarence', 'Lillian')
[Clarence] took his son [Nicholas] to school this morning because he missed the bus. [Nicholas] liked to talk about his sister, [Lillian].
[{('Clarence', 'daughter', 'Lillian'): [('Clarence', 'son', 'Nicholas'), ('Nicholas', 'sister', 'Lillian')]}]
['son', 'sister']