A little confused. Are you replacing the orange side marker on the bumper with a clear 'euro' one, mounted on the fender in the pic below?
What OEM connector are you referring to? In the set-up shown above, the wiring from the connector on the original bumper side marker was lengthened and used on the new marker. Others use signal indicator wiring so they blink. If I was to do this again, I might try that. Oh, and I cut the US bumper to fit the new marker.
Not sure if this helped at all, but welcome and hopefully you're answer will come. Oh, fill out your profile so we nkow what we're dealing with.
Dave M