[Natalia]'s sister [Mary] helped her pick out a Father's Day gift for her father, [Nicholas].
('Mary', 'Nicholas')
[Natalia]'s sister [Mary] helped her pick out a Father's Day gift for her father, [Nicholas].
[{('Mary', 'father', 'Nicholas'): [('Mary', 'sister', 'Natalia'), ('Natalia', 'father', 'Nicholas')]}]
['sister', 'father']