[Hugh]'s mother [Frances] and son [Johnson] worked together to prepare a fresh salad. [David] talks to her son [Johnson] every day.
('David', 'Frances')
[David] talks to her son [Johnson] every day. [Hugh]'s mother [Frances] and son [Johnson] worked together to prepare a fresh salad.
[{('David', 'mother', 'Frances'): [('David', 'son', 'Johnson'), ('Johnson', 'grandmother', 'Frances')]}, {('Johnson', 'grandmother', 'Frances'): [('Johnson', 'father', 'Hugh'), ('Hugh', 'mother', 'Frances')]}]
['son', 'father', 'mother']