[David] took her sister [Lena] out for dinner to celebrate her birthday. [Bobby] invited his sister [Gloria] out to watch the meteor shower. [David] gave her son, [Bobby], blankets for them to sit on and snacks to eat while they watched the meteors.
('Lena', 'Gloria')
[David] took her sister [Lena] out for dinner to celebrate her birthday. [Bobby] invited his sister [Gloria] out to watch the meteor shower. [David] gave her son, [Bobby], blankets for them to sit on and snacks to eat while they watched the meteors.
[{('Lena', 'niece', 'Gloria'): [('Lena', 'sister', 'David'), ('David', 'daughter', 'Gloria')]}, {('David', 'daughter', 'Gloria'): [('David', 'son', 'Bobby'), ('Bobby', 'sister', 'Gloria')]}]
['sister', 'son', 'sister']