Is the rattle from internal looseness of an internal panel a standard feature of the MY10-12 grilles and can they be silenced from the outside?

Whilst I've been aware that both of mine have always rattled, I'm keen to stop the rattle in case it's contributing to induced cabin noise from the front tyres. To remove them for dismantling there's a fair amount of work compared with earlier models due to MY10-12 having bolts fitted from behind the guard liner to hold the top of the lower guard panel which has to be removed to remove the grille, as well as removing the mud-flaps. I might try to get some silicone through the gaps but the panel edges aren't very accessible.

Edit: Closer inspection revealed that the back panel of the assembly is clipped to the front in 3 places down the side adjacent to the door and that the panel was loose in those clips. The clips and surrounding panel are now covered in silicone which has stopped the rear edge from rattling and whilst the front hasn't been addressed, the panel doesn't rattle nearly as much as it did. I don't really think the grilles were responsible for the tyre noise but needed to stop the rattling just in case.