[Cheryl] was sewing a sweater for her sister [Rebecca]. [Dorothy] took her daughter's [Annie] and [Heather] out to dinner one day. Unfortunately, their sister [Rebecca] was away at college and could not join.
('Dorothy', 'Cheryl')
[Dorothy] took her daughter's [Annie] and [Heather] out to dinner one day. Unfortunately, their sister [Rebecca] was away at college and could not join. [Cheryl] was sewing a sweater for her sister [Rebecca].
[{('Dorothy', 'daughter', 'Cheryl'): [('Dorothy', 'daughter', 'Rebecca'), ('Rebecca', 'sister', 'Cheryl')]}, {('Dorothy', 'daughter', 'Rebecca'): [('Dorothy', 'daughter', 'Annie'), ('Annie', 'sister', 'Rebecca')]}, {('Dorothy', 'daughter', 'Annie'): [('Dorothy', 'daughter', 'Heather'), ('Heather', 'sister', 'Annie')]}]
['daughter', 'sister', 'sister', 'sister']