[Adan] called his brother, [Robert], to confirm when [Robert]'s sister, [Margaret], was coming to the dinner.
('Margaret', 'Adan')
[Adan] called his brother, [Robert], to confirm when [Robert]'s sister, [Margaret], was coming to the dinner.
[{('Margaret', 'brother', 'Adan'): [('Margaret', 'brother', 'Robert'), ('Robert', 'brother', 'Adan')]}]