[Nancy] was sad she would n't be able to spend Christmas with her daughter, [Heidi]. [Heidi] had to stay home to care for her brother, [Robert].
('Robert', 'Nancy')
[Nancy] was sad she would n't be able to spend Christmas with her daughter, [Heidi]. [Heidi] had to stay home to care for her brother, [Robert].
[{('Robert', 'mother', 'Nancy'): [('Robert', 'sister', 'Heidi'), ('Heidi', 'mother', 'Nancy')]}]
['sister', 'mother']