[Milton] took his wife [Mary] to Hawaii. [Milton]'s dad [Nicholas] was worried because he had no idea where they were.
('Nicholas', 'Mary')
[Milton] took his wife [Mary] to Hawaii. [Milton]'s dad [Nicholas] was worried because he had no idea where they were.
[{('Nicholas', 'daughter-in-law', 'Mary'): [('Nicholas', 'son', 'Milton'), ('Milton', 'wife', 'Mary')]}]
['son', 'wife']