[Ann] and her sister [Janet] were playing outside. [Ann]'s mother [Lillian] called for her to come inside.
('Janet', 'Lillian')
[Ann] and her sister [Janet] were playing outside. [Ann]'s mother [Lillian] called for her to come inside.
[{('Janet', 'mother', 'Lillian'): [('Janet', 'sister', 'Ann'), ('Ann', 'mother', 'Lillian')]}]
['sister', 'mother']