[Milton] asked his father, [Nicholas] to help him build a birdhouse. [Glen] went to the park with his father, [Nicholas].
('Glen', 'Milton')
[Glen] went to the park with his father, [Nicholas]. [Milton] asked his father, [Nicholas] to help him build a birdhouse.
[{('Glen', 'brother', 'Milton'): [('Glen', 'father', 'Nicholas'), ('Nicholas', 'son', 'Milton')]}]
['father', 'son']