[David]'s father [James] and sister [Lena] joined her for her hike. [Lena]'s son, [Theodore], could n't make it because of work.
('Theodore', 'James')
[David]'s father [James] and sister [Lena] joined her for her hike. [Lena]'s son, [Theodore], could n't make it because of work.
[{('Theodore', 'grandfather', 'James'): [('Theodore', 'mother', 'Lena'), ('Lena', 'father', 'James')]}, {('Lena', 'father', 'James'): [('Lena', 'sister', 'David'), ('David', 'father', 'James')]}]
['mother', 'sister', 'father']