[Chris] was watching a movie with his sister [Martha] and his brother [Charles] when his grandmother [Frances] brought them some popcorn to eat while they watched it.
('Charles', 'Frances')
[Chris] was watching a movie with his sister [Martha] and his brother [Charles] when his grandmother [Frances] brought them some popcorn to eat while they watched it.
[{('Charles', 'grandmother', 'Frances'): [('Charles', 'sister', 'Martha'), ('Martha', 'grandmother', 'Frances')]}, {('Martha', 'grandmother', 'Frances'): [('Martha', 'brother', 'Chris'), ('Chris', 'grandmother', 'Frances')]}]
['sister', 'brother', 'grandmother']