[Linda] made breakfast for her sister [Louise]. [Louise]'s brother [Robert] sat down at the table with a bowl of cereal.
('Robert', 'Linda')
[Linda] made breakfast for her sister [Louise]. [Louise]'s brother [Robert] sat down at the table with a bowl of cereal.
[{('Robert', 'sister', 'Linda'): [('Robert', 'sister', 'Louise'), ('Louise', 'sister', 'Linda')]}]
['sister', 'sister']