[John] and his brother [Douglas] had a fight. They did n't speak to each other for a whole week afterwards. [John]'s grandfather, [Clarence], took the boy to the store to buy some new shoes.
('Douglas', 'Clarence')
[John] and his brother [Douglas] had a fight. They did n't speak to each other for a whole week afterwards. [John]'s grandfather, [Clarence], took the boy to the store to buy some new shoes.
[{('Douglas', 'grandfather', 'Clarence'): [('Douglas', 'brother', 'John'), ('John', 'grandfather', 'Clarence')]}]
['brother', 'grandfather']