[Lena] took her son [Charles] to ice hockey practice. After, she picked up [Charles]'s sister, [Martha], from the park. [Martha] was there playing with her sister, [Pamela], for a few hours.
('Pamela', 'Lena')
[Lena] took her son [Charles] to ice hockey practice. After, she picked up [Charles]'s sister, [Martha], from the park. [Martha] was there playing with her sister, [Pamela], for a few hours.
[{('Pamela', 'mother', 'Lena'): [('Pamela', 'brother', 'Charles'), ('Charles', 'mother', 'Lena')]}, {('Pamela', 'brother', 'Charles'): [('Pamela', 'sister', 'Martha'), ('Martha', 'brother', 'Charles')]}]
['sister', 'brother', 'mother']