[Douglas] called his brother, [Jerry], to confirm when [Jerry]'s sister, [Ann], was coming to the dinner.
('Ann', 'Douglas')
[Douglas] called his brother, [Jerry], to confirm when [Jerry]'s sister, [Ann], was coming to the dinner.
[{('Ann', 'brother', 'Douglas'): [('Ann', 'brother', 'Jerry'), ('Jerry', 'brother', 'Douglas')]}]
['brother', 'brother']