[April] went on a vacation with her brother [Timothy]. [Timothy] liked to play games with his sister, [Janet].
('April', 'Janet')
[April] went on a vacation with her brother [Timothy]. [Timothy] liked to play games with his sister, [Janet].
[{('April', 'sister', 'Janet'): [('April', 'brother', 'Timothy'), ('Timothy', 'sister', 'Janet')]}]
['brother', 'sister']