My wife and I both have an Edge 830. We also have a mix of Garmin & Bontrager lights.
The issue is that both 830s automatically pair with all of the lights. The only way I have been able to deal with this in the past is to install all of the lights on both Garmins and then disable the lights that I don't want connected to that device.
The latest software update on the Garmin has removed the ability to disable individual lights. So I now have the same issue that the lights randomly decide which Garmin they are connected to whether it is on the bike in question or not. Deleting the lights doesn't work because as soon as the light is in range of the Garmin it will reconnect to the light.
Has anyone else had a similar issue and if so how are you dealing with it?