[Mario] was happy to see his aunt [Tracy]. [Tracy] could n't wait for her father, [Harold], to see the gift she bought for him. [Robert] watched his son [Ronald] play catch. [Ronald] tossed the ball back and fourth with his brother [Mario].
('Robert', 'Harold')
[Robert] watched his son [Ronald] play catch. [Ronald] tossed the ball back and fourth with his brother [Mario]. [Mario] was happy to see his aunt [Tracy]. [Tracy] could n't wait for her father, [Harold], to see the gift she bought for him.
[{('Robert', 'father', 'Harold'): [('Robert', 'sister', 'Tracy'), ('Tracy', 'father', 'Harold')]}, {('Robert', 'sister', 'Tracy'): [('Robert', 'son', 'Mario'), ('Mario', 'aunt', 'Tracy')]}, {('Robert', 'son', 'Mario'): [('Robert', 'son', 'Ronald'), ('Ronald', 'brother', 'Mario')]}]
['son', 'brother', 'aunt', 'father']