How do the ini files propegate?

[duxck 1]

I've been trying to figure out how the ini settings propegate.
Like, BaseGame.ini -> DefaultGame.ini -> Game.ini 

If I have: 

DefaultGame.ini
bSettingFooBaar=ValueX 
Game.ini (Saved\Config\WindowsServer\) 
bSettingFooBaar=ValueY 
Game.ini (Saved\GridXY\Config\WindowsServer\)  
bSettingFooBaar=ValueZ

Which would override which? 
And if you have additional settings that aren't added to all game.ini will they still be exectued? Like this:

DefaultGame.ini
bSettingFooBaar=ValueX
FooBar=bool
Game.ini (Saved\Config\WindowsServer\) 
bSettingFooBaar=ValueY 
Game.ini (Saved\GridXY\Config\WindowsServer\)  
bSettingFooBaar=ValueZ
BarFoo=1.0

Would the Game.ini that GridXY uses look like this?

Game.ini (Saved\GridXY\Config\WindowsServer\)  
bSettingFooBaar=ValueZ
BarFoo=1.0
FooBar=bool

And as far as I can tell, the ShooterGame\Saved\  is generated from the ServerGrid.json. So if all settings that I would like to be server specific either should be overridden through the ServerGrid.json or completely ignored in the json and only edit the ini-files manually?