I thought there was a way to explicitly ask to put 2 or more metrics on the same axis (with specific configuration), of course, it can't be automatic, but it could be an interesting option.
Since the configuration of multigraph is done manually, such an option could exist and be set manually as well, adding in my example T1 and T2 explicitly on the same shared axis (because I manually configure it), the software would only care about minimum and maximum numeric values for autoscale, it won't care about unit nor conversion...
It would be my responsibility to not add temperature and humidity on the same axis since it won't mean anything, the software doesn't have to deal with that.
I was just asking if such a feature already exists, if not I could live without it.