Okay...



EDIT: LOL, I just got it! GAWD, I'm so fookin' slow!

I would steer you away from this idea personally.

But the best and really the only way to bond unlike materials

is to use fiberglass matting, but not with polyester resin, you

would need a epoxy resin.

A good way would be to use mechanical fastners such as rivets/screws and to apply a epoxy paste between the 2 parts when you fasten them (be sure to grind the surface to promote a good bond)



You can either hide the screws/rivets from sight, or after the paste dries you can try removing the mechanical fastners and then grinding the areas and then applying fiberglass matting wet out with epoxy resin. In your case leaving those fastners would be a good idea so that fascia doesnt end up in the windshield of some guys Hyundai.

After that dries you would have to grind the areas and then fair the whole thing with some fairing compound, primer and paint, clear.