[Milton] went on a camping trip with his father [Nicholas] and grandfather [Clarence] last weekend.
('Nicholas', 'Clarence')
[Milton] went on a camping trip with his father [Nicholas] and grandfather [Clarence] last weekend.
[{('Nicholas', 'father', 'Clarence'): [('Nicholas', 'son', 'Milton'), ('Milton', 'grandfather', 'Clarence')]}]
['son', 'grandfather']