I didn't mean it in a rude way.

The Original Poster was trying to figure out how to make his blinkie work with his seat bag. There are several ways to do this - if you have the right seat bag, you can clip a blinkie onto it. Or you could possibly mount the blinkie underneath the seat bag. I expressed the opinion that the best solution to the problem was to mount to the rear rack.

I believe that you can mount pretty much any light to a typical rack. But I don't know the kind of rack the OP has, or how the blinkie works.

Looking at the web pictures of the blinky, it looks like it mounts on a standard reflector bracket. In that case, mounting it on most racks would not be difficult - might require longer screws and spacers at most. But *I* can't figure it out from here. The OP will have to figure it out himself.