[John] loved his mother, [Lillian]. [John] and his sister [Janet] went to the park.
('Lillian', 'Janet')
[John] loved his mother, [Lillian]. [John] and his sister [Janet] went to the park.
[{('Lillian', 'daughter', 'Janet'): [('Lillian', 'son', 'John'), ('John', 'sister', 'Janet')]}]
['son', 'sister']