I checked the names of James' children on the Death Notice against the list of children I had, and the only one that doesn't appear is Adam James Douglas, so perhaps he did change his name to Edward George, after all.
This week I finally unearthed baptisms for four of Edward and Elizabeth's children. Edward George Douglas, their firstborn, had JAMES LANDELLS as one of his godparents, which indicates that Edward still had contact with his family at that point. (I'm assuming that this would be brother Adam James, born 1868, and not James Douglas Landells.) Edward senior was a stone cutter/mason, by trade, until circa 1910, when his occupation is given as 'police constable,' on the baptismal record of his daughter Millicent. Their daughter Adelaide was actually Dorothy Adelaide, born 1904.