Mr Barker said his daughter had been due to go on a trip to Omagh on the Saturday, but had said she was not feeling well and James asked if he could go instead.
Victor Barker also told the Omagh Bombing Inquiry that he does not believe his daughter has ever recovered from the guilt that her brother James replaced her on a trip to the Co Tyrone town on the day of the massacre.
Mr Barker told the inquiry how he picked up a copy of a newspaper the next day where there was a picture of James on the front page.
Mr Barker said he also had to identify the body of the brother of a Spanish exchange student who had been staying with his family.
Mr Barker said the funeral of his son in Buncrana was “almost like a state funeral”.