[Mildred] asked her sister [Pamela] to hurry up and get off the phone. [Mildred]'s sister [Tina] told her to wait her turn and be more patient. [Irvin] often goes out for lunch with his sister, [Pamela].
('Irvin', 'Tina')
[Irvin] often goes out for lunch with his sister, [Pamela]. [Mildred] asked her sister [Pamela] to hurry up and get off the phone. [Mildred]'s sister [Tina] told her to wait her turn and be more patient.
[{('Irvin', 'sister', 'Tina'): [('Irvin', 'sister', 'Pamela'), ('Pamela', 'sister', 'Tina')]}, {('Pamela', 'sister', 'Tina'): [('Pamela', 'sister', 'Mildred'), ('Mildred', 'sister', 'Tina')]}]
['sister', 'sister', 'sister']