[Nicholas] went sailing with his sister [Lillian] and his son [Milton].
('Milton', 'Lillian')
[Nicholas] went sailing with his sister [Lillian] and his son [Milton].
[{('Milton', 'aunt', 'Lillian'): [('Milton', 'father', 'Nicholas'), ('Nicholas', 'sister', 'Lillian')]}]
['father', 'sister']