Showing the difference between 1 circuit and the other circuits

Hi,

I've set up my flukso to measure my main circuit, then 8 of my sub-circuits. I have 3 more lighting circuits which I would like to show on my flukso dashboard, in addition or (preferably) instead of, by calculating the difference between the main and sub-circuits.

Can I do this through the /etc/config/flukso file?

Thanks,

Alex.