[Milton] took his mother [Amy] and [Amy]'s mother [Ashley] on a trip to the Grand Canyon.
('Milton', 'Ashley')
[Milton] took his mother [Amy] and [Amy]'s mother [Ashley] on a trip to the Grand Canyon.
[{('Milton', 'grandmother', 'Ashley'): [('Milton', 'mother', 'Amy'), ('Amy', 'mother', 'Ashley')]}]
['mother', 'mother']