[Hugh] went to the baseball game with his son [Bobby] [David] had to pick her son [Bobby] up from school because the schools' bus was broke down. [David] is taking a trip to see her sister [Lynn].
('Hugh', 'Lynn')
[Hugh] went to the baseball game with his son [Bobby] [David] had to pick her son [Bobby] up from school because the schools' bus was broke down. [David] is taking a trip to see her sister [Lynn].
[{('Hugh', 'sister', 'Lynn'): [('Hugh', 'son', 'Bobby'), ('Bobby', 'aunt', 'Lynn')]}, {('Bobby', 'aunt', 'Lynn'): [('Bobby', 'mother', 'David'), ('David', 'sister', 'Lynn')]}]
['son', 'mother', 'sister']