[Amy] has a son named [Dennis]. [Dennis] and his sister [Jennifer] went to the park.
('Amy', 'Jennifer')
[Amy] has a son named [Dennis]. [Dennis] and his sister [Jennifer] went to the park.
[{('Amy', 'daughter', 'Jennifer'): [('Amy', 'son', 'Dennis'), ('Dennis', 'sister', 'Jennifer')]}]
['son', 'sister']