I have yet to see the film myself, but according to @jhull, the men in barracks 4 (excluding Sgt. Sefton, the Influence Character) represent the personal perspective of the Main Character. As stated in the article above:
"The remaining men in barracks 4 supply the MAIN CHARACTER THROUGHLINE. As a collective group dynamic stuck in a SITUATION where they find themselves dancing romantically with one another, they share the same perspective on Sefton’s guilt and on the inner and outer workings of Stalag 17. This truly is a unique structural dynamic. Often the Influence Character role will hand-off from one player to the next—rare is the film that tries this with the personal throughline."