Help with Forum Display options

[Eunos]

On my site, one of the forum sections got to be too big and busy for a single forum. So we broke it up by creating a half-dozen sub-forums.

While some of the community likes it better now, there are "those who refuse to change" that are howling in protest because they want to see everything in one list. They don't want to have to click on each of the 6 sub-forums separately.

Is there a way to have the best of both worlds, with some sort of query that would show them all threads in the forum section as well as in the sub-forums under that section? I've been able to do something close to this by using the getnew function, but that only shows threads containing new posts. That isn't good enough for these people. They want to see everything in a single listing.

Any way to do this?

I'm on 3.8.5, btw.