Thank you very much guys. I did the following:
1. Create 'all games' folder under collections
2. place empty .sub file for collections that I want to appear e.g. Sega Genesis, Super Nintendo Entertainment System
The above creates a new collection on the main screen called 'All Games' and when I go into it, all the games I am interested in are listed in the sub menu.
There is one problem - If I edit the settings.conf file to point to 'All Games', the games are not listed like a typical sub menu, each game is listed as its own system. Is there a way to overcome this?