[Mary] and her mother [Amy] went shopping for [Mary]'s husband [Milton]'s birthday.
('Milton', 'Amy')
[Mary] and her mother [Amy] went shopping for [Mary]'s husband [Milton]'s birthday.
[{('Milton', 'mother-in-law', 'Amy'): [('Milton', 'wife', 'Mary'), ('Mary', 'mother', 'Amy')]}]
['wife', 'mother']