[Glen] took his mother, [Amy], and his sister, [Mary], to the store.
('Mary', 'Amy')
[Glen] took his mother, [Amy], and his sister, [Mary], to the store.
[{('Mary', 'mother', 'Amy'): [('Mary', 'brother', 'Glen'), ('Glen', 'mother', 'Amy')]}]
['brother', 'mother']