[David] asked his mother [Stephanie] if she could read him a story. She was busy, but [Mary], [Stephanie]'s mother, was able to read to [David] instead.
('David', 'Mary')
[David] asked his mother [Stephanie] if she could read him a story. She was busy, but [Mary], [Stephanie]'s mother, was able to read to [David] instead.
[{('David', 'grandmother', 'Mary'): [('David', 'mother', 'Stephanie'), ('Stephanie', 'mother', 'Mary')]}]