Any chance that person was following a different path?I know the folks from the Dis had an experience where 2 of them got to do the bridge thing and the other one wasn't allowed to join them which I felt was super weird. If that was young kids I am certain there'd be some major tears.
Perhaps they were choosing the First Order at each decision point while the other two were following the Resistance. A double agent on a different decision tree with different outcomes. Perhaps leading to a different bridge experience at a different time.
I didn't watch closely enough to see if the DIS group was really a "single party" or if was a "party of 2" and "party of 1" just doing it similar but not exactly the same. In the case of a single family group, I'm guessing little Johnny cannot throw everything to the dark side opposite the rest of the family following the light and end up on a unique and different path. But, I can completely see how two groups who are distinct and independent could make different decisions that lead to different paths, even if it's only a few decisions.
On the one side, nobody wants to miss anything, to do it all (if that's even possible). On the other side, everyone wants decisions that are made to impact the story line and path in unique ways where the decisions have consequences. It cannot be both.