I would like to usr other charachters, but I dont want to lose my current charachter and game.

what system are you on?

Your autosaves will be lost. But as long as you perform a NEW SAVE for your new characters and just make sure you select that save file to save over when playing that character. You should be fine.

I never had an issue on the PS3 or on the PC. I do have manual saves per each character from their current place of play JUST incase I save over one with another character.