[Timothy] and his mother, [Lillian], went to the movie theater. [Lillian]'s father, [Clarence], met them there.
('Timothy', 'Clarence')
[Timothy] and his mother, [Lillian], went to the movie theater. [Lillian]'s father, [Clarence], met them there.
[{('Timothy', 'grandfather', 'Clarence'): [('Timothy', 'mother', 'Lillian'), ('Lillian', 'father', 'Clarence')]}]
['mother', 'father']