How to tell a folder from a launcher in ~/.local/share/applications

[Michele]

Hello,

I have created a new directory in my Applications > Office menu and I
would like to copy inside it the launchers for a different version of
openoffice that I have installed (as well as different user profiles).
Rather than using System > Preferences > Main Menu which is slow and
painful I would like to make copies of the existing launchers and edit
them with a text editor.

The problem is that I cannot understand how to place a launcher
(.desktop file) into a specific subdirectory in my Office menu.
~/.local/share/application is "flat" and I do not know where to look
at into the .desktop file to understand where the launcher will appear
in the menu tree.
My directory is in ~/.local/share/desktop-directories but I do not
know how to link my directory to the launchers.

Another question: can I then move all the launchers to /usr/share/ so
that all the other users can have the same menu entries?

Cheers,

Michele