I think it is a bad idea simply because we already have so many forums and sub-forums that it is impossible to check them all.
An example is gear, electronics, and electrical systems, do we really need three forums for this ? I find it annoying to click on gear and then have to click on electronics and then have to click on electrical systems all to find out what is going on in the gear forums, and then when you post in a subforum like electronics nobody answers it because the posts are spread out so much. Maybe the diesel subforum has a use. Me, I'd prefer just "gear" that had all of those subforums posts in it.
Another example is cruising and liveaboards with the separate provisioning forum, are cruising and living aboard really so different that they need their own forums ? Maybe, I would argue yes they are different enough for their own forums. But provisioning, few people post to it even when they do have a provisioning issue, they end up posting in general or in cruising instead, because the provisioning subforum is lost under live aboard and cruising and nobody ever seems to read it or post to it. Provisioning is one of the subjects I am most interested in and even I would like to see that subforum disappear, at least that way I'd know I wasn't missing any provisioning posts by not checking the subforum on a regular basis, because those posts would be in cruising or general or somewhere else that I do check often.
So I guess I'm saying I don't like the idea of a family forum simply because I think we already have enough forums and it would end up being yet another series of mouse clicks. At some point those mouse clicks are like the sound of little mouse feet running through a maze.
Obviously not something for everyone on here, but hey it may be a case of build it and they will come......
Or maybe just another oubliette for posts.