[Robert]'s son [Ronald] and daughter [Angelica] baked a cake with [Angelica]'s brother, [Mario]. [Marie] took her son [Ronald] to the mall to shop for school clothes.
('Marie', 'Mario')
[Marie] took her son [Ronald] to the mall to shop for school clothes. [Robert]'s son [Ronald] and daughter [Angelica] baked a cake with [Angelica]'s brother, [Mario].
[{('Marie', 'son', 'Mario'): [('Marie', 'son', 'Ronald'), ('Ronald', 'brother', 'Mario')]}, {('Ronald', 'brother', 'Mario'): [('Ronald', 'father', 'Robert'), ('Robert', 'son', 'Mario')]}, {('Robert', 'son', 'Mario'): [('Robert', 'daughter', 'Angelica'), ('Angelica', 'brother', 'Mario')]}]
['son', 'father', 'daughter', 'brother']