[Constance] and her sister [Stephanie] went out to lunch with [Constance]'s sister [Martha].
('Martha', 'Stephanie')
[Constance] and her sister [Stephanie] went out to lunch with [Constance]'s sister [Martha].
[{('Martha', 'sister', 'Stephanie'): [('Martha', 'sister', 'Constance'), ('Constance', 'sister', 'Stephanie')]}]