It sounds to me, though I am not entirely clear exactly what all you have done and changed, that you are merely creating children of blueprints. That is good, but the game doesn’t look for children and automatically replace content because it has a child. You must make a new bluperint, or a child, and then have either gamedata and/or gamemode blueprints reference the new assets. Then you have the map override the gamedata and gamemode in the world settings. The gamemode and gamedata blueprints are everything you have to start from, but they eventually reference just about every asset that makes the game at some point so adjusting that hierarchy at points allows you to inject your own assets to the game.