Auto Load Specific Configs

How do I set up RetroArch to load a different config file depending on the core selected?

I have downloaded RetroArch 1.6.0, and am trying to set it up. The eventual goal is to give it to my 6 year old to play with, so things need to be easy to use.

I have RetroArch in one directory, let’s call it C:/main.

I have loadable assets in various other directories, such as:

C:/foo/emulator1 C:/foo/emulator1/roms C:/foo/emulator1/saves

I would like to start RetroArch from C:/main, but when I go to play a game, such as Super Mario 64, and it loads a specific core, I want it to load specific core options from:

C:/foo/emulator1/n64.cfg

Ideally n64.cfg would only detail changes from C:/main/retroarch.cfg.

So, how do I convince RetroArch to do this? Telling a 6 year old to go in and select change configuration each and every time will not end well.