If I use a relay like fibaro double switch 2, can I operate the lights using both the wall switch, on/off and also via HA on/off (even if the wallswitch is off) independently off each other?
What im trying to understand, is that it will be failsafe in a family where some perhaps not want to use the HA system…
Yes this is what they are designed to do. The switch is connected to the relay and acts as a toggle (switching the relay to the opposite state) When not touched the switch does nothing therefore the HA button can control the relay with the switch in OFF, although its now not really an on off switch any more.
