[Nancy] was playing games with her son [Robert]. [Robert]'s sister [Linda] did n't want to join them.
('Nancy', 'Linda')
[Nancy] was playing games with her son [Robert]. [Robert]'s sister [Linda] did n't want to join them.
[{('Nancy', 'daughter', 'Linda'): [('Nancy', 'son', 'Robert'), ('Robert', 'sister', 'Linda')]}]
['son', 'sister']