I have a theory that Crying Child could be the Balloon Boy for three reasons:
1st - although it is unknown why the Nightmare Balloon Boy appears, the minigames can only be played after night 8 is completed, I think it serves to reveal that the Crying Child will become the Balloon Boy;
2nd - Balloon Boy probably only comes to steal the batteries for Jeremy to be defenseless (Crying Child needed his flashlight to survive), I don't know if it makes sense for Balloon Boy to be Crying Child or not;
3rd - Balloon Boy's laughter can attract Springtrap to other rooms, it could be possible that Balloon Boy is the son of William Afton.
Who agrees with this theory.