[Heidi]'s brother [Robert] and her went to get ice cream. [Robert] took his sister [Louise] out to dinner for her birthday.
('Louise', 'Heidi')
[Robert] took his sister [Louise] out to dinner for her birthday. [Heidi]'s brother [Robert] and her went to get ice cream.
[{('Louise', 'sister', 'Heidi'): [('Louise', 'brother', 'Robert'), ('Robert', 'sister', 'Heidi')]}]
['brother', 'sister']