[Harold] made a sandwich for his son [Louis]. [Louis]'s brother [Robert] ate an apple instead. [Harold] helped his grandson [Jeffrey] cut the lawn for [Jeffrey]'s mother, [Dorothy].
('Dorothy', 'Robert')
[Harold] helped his grandson [Jeffrey] cut the lawn for [Jeffrey]'s mother, [Dorothy]. [Harold] made a sandwich for his son [Louis]. [Louis]'s brother [Robert] ate an apple instead.
[{('Dorothy', 'brother', 'Robert'): [('Dorothy', 'father', 'Harold'), ('Harold', 'son', 'Robert')]}, {('Dorothy', 'father', 'Harold'): [('Dorothy', 'son', 'Jeffrey'), ('Jeffrey', 'grandfather', 'Harold')]}, {('Harold', 'son', 'Robert'): [('Harold', 'son', 'Louis'), ('Louis', 'brother', 'Robert')]}]
['son', 'grandfather', 'son', 'brother']