Could just be a nickname... Like some people called JFK "Jack Kennedy".


Jack is a common nickname for people named John. So it definitely can be that.


The big remaining question is whether Darren Mann, who will play Jack Dutton in 1923, is actually John Dutton II (aka Kevin Costner's character's father) or if he is John Dutton Jr.'s brother and Kevin Costner's character's uncle.


I’m the preview for 1883 James Dutton is shot there are two boys in the cabin. Jamie’s dad made a comment about John stealing the land and doing something to family. I think Johns dad or John himself took out a family members that was supposed to inherit the land.


That’s Spencer Dutton in that scene. James’ other son.


I believe Jack Dutton (Darren Mann) is supposed to be Jacob Duttons (Harrison Ford) son. Darren is mid 30s, so that would make his character close in age to Spencer and way to old to be Johns son. And since we didn’t see a 3rd son of James in the Yellowstone flashback, being Jacobs son seems makes sense. When it comes to the family tree, I’m of the mind that they never had a hard family tree in the early days of the show. When the flashback scenes and 1883 came to be, they didn’t jive perfectly with the 5 generations idea. Continuity errors like this in tv happen when they are only written one season at a time. The concepts for things down the road exist, but not the details. I’ve always maintained that they are going to fudge the ages a bit and squeeze in a generation between John Sr and John II. He’ll be a non-John, so the naming titles work out, albeit in an unconventional way. But he’ll be born around 1900-1905-ish. Meaning John (b. 1878-9?) had him in his early 20s, and that son goes on to have John II, possibly during the course of 1923, who then goes on to have John III in 1955. To me, this is how you make the names, ages, and generations work.