[Pamela]'s sister [Martha] and brother [Chris] helped [Martha]'s grandfather, [James], with buying a new car.
('James', 'Chris')
[Pamela]'s sister [Martha] and brother [Chris] helped [Martha]'s grandfather, [James], with buying a new car.
[{('James', 'grandson', 'Chris'): [('James', 'granddaughter', 'Pamela'), ('Pamela', 'brother', 'Chris')]}, {('James', 'granddaughter', 'Pamela'): [('James', 'granddaughter', 'Martha'), ('Martha', 'sister', 'Pamela')]}]
['granddaughter', 'sister', 'brother']