[Theresa]'s nephew [John] is going with her to town. [George] went to pick up his son [John] from the baseball practice.
('George', 'Theresa')
[George] went to pick up his son [John] from the baseball practice. [Theresa]'s nephew [John] is going with her to town.
[{('George', 'sister', 'Theresa'): [('George', 'son', 'John'), ('John', 'aunt', 'Theresa')]}]
['son', 'aunt']