marli van breda , 16 , suffered serious head injuries in january attack .
she was moved to a rehabilitation clinic after six weeks in hospital .
now released , marli has no recollection of the horrendous ordeal .
but she can walk and talk - and her sense of humour is intact .
parents and eldest brother were killed in axe attack at south african home .
her other brother , henri , escaped with light injuries and rang the police .
henri has been kept away from sister over fears he may traumatise her .
the 22-year-old apparently ` giggled ' as he reported his family 's murder .