[George] took his daughter [Ann] out for nachos. [George]'s son [Douglas] played with his friend instead.
('Ann', 'Douglas')
[George] took his daughter [Ann] out for nachos. [George]'s son [Douglas] played with his friend instead.
[{('Ann', 'brother', 'Douglas'): [('Ann', 'father', 'George'), ('George', 'son', 'Douglas')]}]
['father', 'son']