> CHD files are searched in this full folder, plus in a gamename sub-folder > automatically, (d:\emulators\mame\x64binary\roms\area51\area51.
Just beware that some CHD based games are not named after their folder name Some CHD files have entirely different names that not necessarily match the name of the folder they are in. Your example shows matching names (area51), but what would happen if the folder was named "area51" and you had two different chd files inside of it called "area643.chd" and "gd456.chd"? Silly name examples, but this situation does happen.