[Hugh] and his wife [David] had a great time playing doubles with [Hugh]'s son [Michael] and [Michael]'s wife [Gloria].
('David', 'Gloria')
[Hugh] and his wife [David] had a great time playing doubles with [Hugh]'s son [Michael] and [Michael]'s wife [Gloria].
[{('David', 'daughter-in-law', 'Gloria'): [('David', 'son', 'Michael'), ('Michael', 'wife', 'Gloria')]}, {('David', 'son', 'Michael'): [('David', 'husband', 'Hugh'), ('Hugh', 'son', 'Michael')]}]
['husband', 'son', 'wife']