[Nicholas] took his son [Dennis] fishing. [Nicholas] and [Dennis] stopped to give [Dennis]'s sister, [Mary], some fish.
('Mary', 'Nicholas')
[Nicholas] took his son [Dennis] fishing. [Nicholas] and [Dennis] stopped to give [Dennis]'s sister, [Mary], some fish.
[{('Mary', 'father', 'Nicholas'): [('Mary', 'brother', 'Dennis'), ('Dennis', 'father', 'Nicholas')]}]
['brother', 'father']