[Andrea] waited for her mother [Lillian] to pick her up at the bus stop. While she waited, she called her sister [Ann] on the phone.
('Ann', 'Lillian')
[Andrea] waited for her mother [Lillian] to pick her up at the bus stop. While she waited, she called her sister [Ann] on the phone.
[{('Ann', 'mother', 'Lillian'): [('Ann', 'sister', 'Andrea'), ('Andrea', 'mother', 'Lillian')]}]
['sister', 'mother']