VM-3P75CT role as AC-Load - position settings

Question regarding VM-3P75CT Energymeter:

In Victron Connect you can select the role of the energy meter, wether it is a grid meter, pv inverter, ac load or generator.

When you select pc inverter, you can also select the position and depending on that setting it is shown at different positions on your dashboard.

I have it mounted on AC-Out right before my heating system. It is not measuring the complete AC-Load, just the energy for the heating system, but when I select AC-load, I cannot select any position. It is also not shown on the dashboard and AC-Load from the Multis is still showing the complete power consumption for my house + heating system. I would like to substract the power from the heating system from the complete load, so I have seperate values for the house and for the heating system. Is this something I could fix with Node:Red?

FW of the VM-3P75CT is 1.08.

Am I missing something or what´s the trick with this energymeter?