[Nicholas]'s son [Milton] went to the baseball game with his sister [Nancy], who was sick.
('Nancy', 'Milton')
[Nicholas]'s son [Milton] went to the baseball game with his sister [Nancy], who was sick.
[{('Nancy', 'nephew', 'Milton'): [('Nancy', 'brother', 'Nicholas'), ('Nicholas', 'son', 'Milton')]}]
['brother', 'son']