Henry Nissen (hired 11-4-1908) and Frank Owenby (hired 1-11-1909) were the engineers on the Alamosa-Chama section of the San Juan in 1950 while John Dieckman (hired 12-7-1905) and Jim Connor (hired 11-7-1906) were the engineers on the Durango-Chama section. Chances are at least two of these men were in the photograph. I can't say for sure.
Three conductors rotated on the runs: Henry Hines (hired 10-1-1897), Stamey Edminsten (hired 11-12-1898) and someone else. In Jimmy Blouch's posts I have seen M.E. Morgan, E.J. Hurley, Charles Knight, R.N. Moore and N.W. Roberts on the train as conductor. All were hired before 1910.
Based on the photo of Henry Hines on the last run and comparing him to the picture of the conductor strolling at Gato, I suspect that was him.
The fireman at Durango was short and fairly young and the trainman riding the coaches also was youngish. I don't know their names or how long they stayed with the railroad.