[Clarence] took his daughter [Nancy] to ballet class. [Nancy] took her daughter [Lorraine] to see her very first ballet performance.
('Lorraine', 'Clarence')
[Nancy] took her daughter [Lorraine] to see her very first ballet performance. [Clarence] took his daughter [Nancy] to ballet class.
[{('Lorraine', 'grandfather', 'Clarence'): [('Lorraine', 'mother', 'Nancy'), ('Nancy', 'father', 'Clarence')]}]
['mother', 'father']