Can you replace a CPU-controlled character with a human in Super Mario Party?
After having played the game myself for quite a bit, I have tried this too and was not able to find anything in the settings menu during a game. Im not sure the exact reason, I remember being able to do this in the N64 Mario Party's, but Im guessing its relating to the fact that you choose Characters and CPU's before you even get into the world to start a game. The only way to change this is to back out to the start menu.