FDA considering technique for three-parent embryos

I'm pretty sure I've discussed chimerism on here before (I know I've at least talked about mosaicism), but in case I haven't, the idea has nothing to do with Frankenorganisms created by smushing bits of other animals together. A genetic chimera is an organism that has collections of cells with at least 2 different sets of DNA. We get half of our DNA from one parent and half from the other, but normally all of our cells get the same "mom set" and the same "dad set," so instead a chimera has more than one "mom set" and more than one "dad set". Usually this happens when two eggs are fertilized by separate sperm and later fuse, creating an individual with some cells with "mom set A" and "dad set A" from the first fertilized egg and other cells with "mom set B" and "dad set B" from the second.

Currently, the FDA is mulling over a technique for test-tube embryos that involves a sort of chimerism in the sense that the embryo produced would have three parents. This would be achieved by taking just the mitochondria from a donor egg, replacing the mother's egg mitochondria with those of the donor, and then fertilizing the egg and continuing on as normal for in-vitro. It's not quite as obvious a chimera because all that's being added from the third parent is a set of organelles, but mitochondrial diseases are a pretty big problem considering they control energy production. They also house their own DNA, so these diseases are passed on from mother to child. As such, being able to replaced genetically faulty mitochondria in an otherwise healthy egg cell would be a huge help for the child later in life.

What I find interesting is the amount of backlash this is facing. Anything involving embryos is going to get religious groups riled up. Is it natural? Well, no. (Of course, "natural" is a stupid word to begin with, but that's aside the point.) But technically at the point of the swap, the egg isn't even fertilized yet, so you're in no way harming any sort of embryonic form, and this is a procedure that could save kids who would've otherwise inherited these mitochondrial diseases a lot of hassle later on. The other fear is that if we can "tweak" DNA like this, scientists will abuse this to create designer babies by only taking the best DNA from however many parents. I'm pretty sure that's not how it works. This is only dealing with a very small subset of DNA that isn't even inherited in the same way that the rest is, so the mechanism is completely different.

I know this won't get far with all the fear mongering going around, but if it were to go through, we'd be doing a lot of people a lot of favors.