EDIT: The pizza example below is not my use case, it was merely used for demonstration.
My use case contains grouped system options that can either be turned on/off completely as a group or be turned on/off individually.
With checkboxes, when not all options are selected, an often used convention is to use a rectangle instead of a checkmark:
Now imagine I have a list of switch options and a "header" switch, which turns the whole group on/off.
What would be the best way to convey the same thing with a switch control?
I had a look at these questions:
An alternative to Indeterminate checkboxes?
What is the best interface for multi selecting from a list?
But they were not really helpful in terms of switches.
I had something like this in mind but it is kinda horrible looking....