audio – Setting a Bluetooth headset to switch between itself and the PC depending if it is docked or not

As IT manager for our company I have had a number of requests from users to be able to have their Bluetooth Headphones be the primary sound for everything that happens on the computer, but once they dock the headset the sound switches over to the computer speaker. So if the sales rep has the headset on, all calls and system sound come across the headphone, but once the person docks the headset the sound switches over to the computer. We are using Sennheiser SDW 60 headset. I would guess that the only way this is possible is with some kind of application.