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