Q:

Update Bootstrap Switch with Leaflet Layer Group

I have this JSFiddle that shows two example layers that can be toggled on and off using the Bootstrap Switch to add and remove them from the map; this works fine. 
The problem I am having is updating the state of the individual layers switches when the group switch is toggled.  As per the example I can create a switch to add the group of layers to the map, however the switches for the individual layers do not update to show the user that is a layer that is effected by the group of layers being added. 
I thought this might be possible through the hasLayer method but I'm not entirely sure how this would be implemented. 

A:

Add the following line in the onSwitchChange event handler of your group switch:
$("[name='my-checkbox2'], [name='my-checkbox3']").bootstrapSwitch('state', state, true);

Updated JSFiddle: https://jsfiddle.net/s537t380/26/
Reference:
http://www.bootstrap-switch.org/methods.html

The method state can receive an optional third parameter skip.  if true, switchChange event is not executed.  The default is false.