Stop listing of contents of container for some items but not all

I have a room which contains a sentry box (enterable open unopenable container)

The sentry box contains a soldier, and a bench (on which are some objects)

I would like the room description to list the sodier (e.g. sentry box (in which is a soldier), but not to list the bench.

When you enter the sentry box then I want it to list everything in there, i.e. In the sentry box you can see…soldier, bench (on which is x).

I’ve considered making the sentry box a room, but that causes other issues.

Have you tried making the bench scenery? There’s some weirdness with scenery supporters and contents listing which I’ve never fully understood, but if making it scenery doesn’t work, there should be a single rule you can turn off to fix that: use the RULES command to find its name.