[Jeff] went with his grandfather [Clarence] and brother [Robert] to the park to play some baseball.
('Robert', 'Clarence')
[Jeff] went with his grandfather [Clarence] and brother [Robert] to the park to play some baseball.
[{('Robert', 'grandfather', 'Clarence'): [('Robert', 'brother', 'Jeff'), ('Jeff', 'grandfather', 'Clarence')]}]
['brother', 'grandfather']