Try using some "flash break tape" taped over the cracks on the finish side of the trim, then brush MEK over the cracks on the back side of the trim with an acid brush, and allow to dry. Its a solvent and will melt the plastic to rejoin it, without using glues. It makes the repaired joint as strong as the base plastic. Once dry, you can sand the part, primer, add a skim coat of evercoat polyester filler to the small defects at the crack area, and repaint.