[Lena]'s mother, [Frances], had finished making dinner. [Frances] told [Lena] to call [Lena]'s sister, [David], to come set the table. [David] and her sister [Lynn] played golf together. [David] won easily.
('Lynn', 'Frances')
[David] and her sister [Lynn] played golf together. [David] won easily. [Lena]'s mother, [Frances], had finished making dinner. [Frances] told [Lena] to call [Lena]'s sister, [David], to come set the table.
[{('Lynn', 'mother', 'Frances'): [('Lynn', 'sister', 'David'), ('David', 'mother', 'Frances')]}, {('David', 'mother', 'Frances'): [('David', 'sister', 'Lena'), ('Lena', 'mother', 'Frances')]}]
['sister', 'sister', 'mother']