dynamic menu with endless possible submenus

I am creating a Dynamic Menu, like for a menu bar. It creates itself according to what is read from a config file.
so if for example in my configuration file i have "Vehicles/4Wheel/Cars"

My Menu should look like

Products
Vehicles -----4Wheel ------ Cars

so there opens 2 Submenus from the root menu.

I am wondering how is the best way to keep track of this. As of now i only managed to do it for having one sub menu by:
std::map< QString, QMenu* > m_SubMenus;
By keeping track of my Menus. QString is the name of the Action under the root menu, like Vehicles in the above example.

I need to keep track of them since the user can modify these menus at runtime.

Any good idea?