[Glen]'s grandfather is [Clarence]. [Amy] took her son [Glen] to the football game.
('Amy', 'Clarence')
[Amy] took her son [Glen] to the football game. [Glen]'s grandfather is [Clarence].
[{('Amy', 'father', 'Clarence'): [('Amy', 'son', 'Glen'), ('Glen', 'grandfather', 'Clarence')]}]
['son', 'grandfather']