[Jerry] and his grandfather [Clarence] like to play chess together. [Douglas] went to the wedding ceremony for his brother [Jerry].
('Douglas', 'Clarence')
[Douglas] went to the wedding ceremony for his brother [Jerry]. [Jerry] and his grandfather [Clarence] like to play chess together.
[{('Douglas', 'grandfather', 'Clarence'): [('Douglas', 'brother', 'Jerry'), ('Jerry', 'grandfather', 'Clarence')]}]
['brother', 'grandfather']