[Theresa] invited her sisters, [Amy] and [Lillian], to a party.
('Lillian', 'Amy')
[Theresa] invited her sisters, [Amy] and [Lillian], to a party.
[{('Lillian', 'sister', 'Amy'): [('Lillian', 'sister', 'Theresa'), ('Theresa', 'sister', 'Amy')]}]
['sister', 'sister']