[Nicholas] played catch with his son [Glen]. Later, he went out to eat with his own father, [Clarence]
('Glen', 'Clarence')
[Nicholas] played catch with his son [Glen]. Later, he went out to eat with his own father, [Clarence]
[{('Glen', 'grandfather', 'Clarence'): [('Glen', 'father', 'Nicholas'), ('Nicholas', 'father', 'Clarence')]}]
['father', 'father']