I’m not exactly sure what you are doing above. What I do know is that can fry your switch by jumping connections. Install you smart switch in the box with load. And follow the line-switch-load-switch-1 wiring diagram. You will not need the neutral or line wires that already exist in the add-on box. You can just cap each of them off.
Obviously I’m only guessing your configuration from what you said above. Pictures or diagrams would be helpful.