To add a circuited device to a switch group that is not already circuited, use the Connect Device to Switch Group command with the following procedure.
The Device is Already Circuited dialog box will appear. You must indicate if you want to Uncircuit the Device or Circuit the Switch. Note that the box provides spaces to accommodate devices with multiple loads so you may chose which loads to move to the circuit. These options will not be active if only one load is present.
Uncircuit the Device will remove the device from the circuit, remove all loops drawn to the device, and replace the switch group label.
Circuit the Switch will add all other devices on that switch to the circuit, place a circuit label and a switch group label by all devices, and update the panel schedule. You will then need to run the Homerun and Loop command to loop the switch.