They'll be molded in the assembly of the frame--it would cost more and be weaker to make them as a separate step and bond them to the frame.

If S&W declines to warranty the repair and it was mine, I'd consider doing a bang-up job of degreasing and prepping the frame, blocking off the area and J-B'ing it...maybe with some stainless cross pins and fiber in the J-B.

And send the aftermarket assembly back to the vendor, and demand a refund...