How to combine different energy values from devices in Energy Dashboard

I have a water heater with a resistor and a heat-pump. The heater integrates with HA and I have the energy values of both components.

Is it possible to add them to get the “water heater energy”?

Secondly, I’m tracking energy at the same outlet with a Shelly Plug S since I also charge a battery vaccuum there. With all of these values in the Energy Dashboard I get negative untracked comsumption since I’m measuring the same energy more than once (heater reported values and outlet reported values).

Is there a way to indicate that the heater values are a sub-part of the outlet values, similar to how grid comsuption is one value and then each device adds to that?