"His head injuries meant they had to remove the top of his skull to relieve the brain swelling and he's lost a significant amount of memory.
"His visits are still restricted because he hasn't been told that Tom was killed in the crash yet.
"I think that's so he can just concentrate on recovering.''
His family are hoping Mr Murphy will make as full a recovery as possible but they have not yet been given a definitive prognosis.
"He's talking and he has taken his first few steps, but the doctors can't really say how far his recovery will take him. He could already have all he ever will or he could go backwards again at any time, apparently.''
Mr Morison's death is to be the subject of a coronial inquest.
Police had not yet laid any charges against Mr Murphy in relation to the crash, the family member said.