I have one small suggestion: perhaps we should call it a "sub" board or some other term because calling it a "child" board can sound like it is a place for children (that was my thought before I read the explanation) and this may have the opposite effect from the one we want. Just a thought.
You're quite right. It does sound rather contradictory in this situation.
"Child board" is the terminology used by Simple Machines in the admin section. When I create a new board I have to put in a location. The options are "before," "after," or "child of." It has nothing to do with being a board created for the sole use of children, of course.
We did have a few other
sub-boards at one time but they were merged into larger ones to make them more visible. That was before we updated. The layout of the forum is better now as the sub-board has its own separate panel whereas before it would have appeared as a small text link tacked underneath a main heading.
I don't know if I can change the wording on the index to something else other than "Child Board," but I'll look into it.