I am not 100% certain on this, but I do not believe you can limit your main navigation sub categories to display only on specific pages – at least not with one main nav menu.
My thought is that you may need to create separate navigation menus for the separate/specific pages needed – with the appropriate subcategories for those specific pages.
However, since I am not 100% certain I am correct with my thinking, I will forward this onto the JA Development Team for review and (hopefully) further comment as to whether the function you desire can be achievable via one main nav menu.