Robert Burton Widener (not Widner) was a half brother of my great-grandfather JB Widener.
Jasper Newton Widener was his father. I am not sure if Mary Jane Barton was his mother, as I said. He was a half brother of JB.
There were a total of 11 Widener children. I am researching the 1/2 brothers and sisters at this time and found this thread on the message board.