A question about save game to slot

Hello. I’m going through saving and loading problems lately. Last problem I encountered was a cast fail to my save game. I did a little research about it and get the answer that it can happen because two save game objects are saved into one slot. My question is, what actually I need to put save game object pin when saving game to slot ? I have a logic in my character bp that as soon as game starts, it checks if there are any save game exist, if not it creates a save game object and stores it in a variable. Do I need to cast to my character BP, get that save game object and use it as save game object whenever I need to save game in my other blueprints ? Sorry if my question is silly but I got confused.