If you are maintaining your config files from the gui, then there is no
way to do it.
If you are maintaining the config files by hand, then you can add any
kind of Perl code in there that you like. You could add the group
definitions in the main config and then load them in the per-machine
configs almost exactly as you show in your example. The caveat is that
once you start doing this, you cannot use the gui to make any further
changes to the configs or it will mess things up.
