[Heidi] and her sister [Lorraine] were playing outside. [Heidi]'s mother [Nancy] called for her to come inside.
('Lorraine', 'Nancy')
[Heidi] and her sister [Lorraine] were playing outside. [Heidi]'s mother [Nancy] called for her to come inside.
[{('Lorraine', 'mother', 'Nancy'): [('Lorraine', 'sister', 'Heidi'), ('Heidi', 'mother', 'Nancy')]}]
['sister', 'mother']