I've had a look at some of my info and you say that you don't remember your Grandfather having a brother called John, well, John's middle initial is .J. so I can only assume that James was his middle name and that his brothers and sisters called him James instead of John.
Here's some more info on John (James)... John was married to ? in 1899 in Middlesbrough (I believe), the story goes that he had a house keeper by the name of SARAH JACKSON nee McFADYEAN, and they ended up getting together and having a little girl called CONNIE. I believe that they told people that they were married, (Sarah changed her name to ALDER). John died when Connie was about 12 / 13 years old, I've been told that it was in an accident at work.
I don't know whether this would make any sense to you, but I strongly believe that we are related. John is my GGGrandfather.
Hope to hear from you soon...
P.S. Where are you from? Most of my family live in Middlesbrough! I live in Dorset at the moment.