[Heidi] went to the store with her sister [Lorraine]. Later that day, [Heidi] had tea with her sister [Linda].
('Linda', 'Lorraine')
[Heidi] went to the store with her sister [Lorraine]. Later that day, [Heidi] had tea with her sister [Linda].
[{('Linda', 'sister', 'Lorraine'): [('Linda', 'sister', 'Heidi'), ('Heidi', 'sister', 'Lorraine')]}]
['sister', 'sister']