This submods will add a new menu icons & events for Dac. It changes the menu's icons, not the banners.
Now, Khazad-dûm will have as strat map banner the Doors of Durin. This is a minimod specifically created for Divide & Conquer V3.
Go inside your Third Age folder, paste the compressed file and unzip it, yes to overwrite all the files, play, enjoy.
PS: If you don't get the warning for overwriting the files, you're not correctly installing it.
PS2: I don't know if this would be compatible with old versions from Dac, Third Age Reforged or Third Age vanilla, feel free to test it. But first at all, make a backup copy.