[Clarence] helped his grandson [Douglas] cut the lawn for [Douglas]'s mother, [Lillian].
('Lillian', 'Clarence')
[Clarence] helped his grandson [Douglas] cut the lawn for [Douglas]'s mother, [Lillian].
[{('Lillian', 'father', 'Clarence'): [('Lillian', 'son', 'Douglas'), ('Douglas', 'grandfather', 'Clarence')]}]
['son', 'grandfather']