[Lillian]'s son, [Douglas], never got along with [Lillian]'s other son, [John].
('John', 'Douglas')
[Lillian]'s son, [Douglas], never got along with [Lillian]'s other son, [John].
[{('John', 'brother', 'Douglas'): [('John', 'mother', 'Lillian'), ('Lillian', 'son', 'Douglas')]}]
['mother', 'son']