This is a feature request.

Currently, we can configure Dolphin to open new tabs "after current tab" or "at end of tab bar".

I think there should be a checkbox beneath "after current tab" with something like "only if new tab is child".

This is to follow web browsers default behavior, which I believe it's the most intuitive and optimal: if I'm opening a new related tab, like by middle-clicking a child folder, this tab should open next to current (in case of a web browser, this happens if you middle-click a link within the page). But if I'm opening a new independent tab, like by middle-clicking an item from Places or by pressing Ctrl+T, then the new tab should open at the end of tab bar.