Replacing lower front grille

Is it possible to replace the lower front grille without taking off the front bumper?  I've looked at the guides on removing the front bumper and they just show the lower front grille as if it was an integral part of the front bumper.  You can buy the grille and its two side vents as spare parts, but I can't find anything that describes how they are fitted.  I'd guess they just clip in, like the main grille, but does anyone know for sure?

I just hit a stationary pheasant standing in the middle of the M4, so the left side of the lower grille has been replaced by feathers.