I also added a rear fog light but every one knows what they look like.
Here is how I wired it.
I put a dual filament socket and bulb. I wanted to have it on as a parking light and wire it to a switch so that it will still be a fog light.
After a little while I also wanted a flashing brake light too.
Here is the schematic:
I still haven't added the flashing brake light relay but in theory it will work. This should isolate everything and allow the fog light to flash when stepping on the brake even with the switch for the fog light on.
The other two are in and working perfectly.