Nesting tools as submenus in the main Shotgrid menu

So I have a number of tools I insert into DCCs via the Shotgrid menu. What I’d like to do is nest related items, so that instead of multiple entries in the shotgrid menu, there’s just one, you hover over that and it displays a submenu with several apps (the way that when you click on Project (first entry in the menu) you get a sub menu with a whole bunch of other tools).

Any idea how this can be done? Thanks very much.