The copy-to-child-virtual-sensor functionality was hastily added, you may recall. So I'm now working at cleaning that up, and ultimately making that the central interface of the plugin, with the function generator secondary (but I'm not there yet). One of the other requests was that there be a way to stop the copy action, so the enabled/disabled state now does that. For the moment, if you don't want to use the function generator, just set a large period and interval; this will minimize the CPU effort there, which is already miniscule, anyway.