Organ harvest, yes.
But also - locate the various missing pieces of the original "elite" bloodline, and reconstitute it. Why do you think the cabal have tried to keep the "line" pure through incest/intermarriage? Even to the point of retardation/physical deformation/genetic diseases (hemophilia, colorblindness, etc.).? Even when they "outbreed" they make sure that there is some cabal lineage (like Diana). Now, they can just recover the genetics that has been scattered far and wide through the population via byblows and rebuild the original DNA configuration. That can be generated on DNA synthesizers and then it's just a matter of inserting the artificially generated chromosomes into an egg that has been emptied of native DNA, and surrogate that elite construct to term.
This is, I fear, the deeper agenda. Reconstructing the progenitor of their "line."