[Nancy] picked up her brother [Dale] from the airport. Then they went to her sister [Amy]'s house for lunch.
('Dale', 'Amy')
[Nancy] picked up her brother [Dale] from the airport. Then they went to her sister [Amy]'s house for lunch.
[{('Dale', 'sister', 'Amy'): [('Dale', 'sister', 'Nancy'), ('Nancy', 'sister', 'Amy')]}]
['sister', 'sister']