Yes, all the DNA being a single DNA in multiple locations (quantumly speaking) is an oversimplification.
You could very much say that each time a cell divides, it asks the parent DNA structure, same cell or new cell? And thus, the body can change and heal over time.
DNA has 12 layers, and we only discuss one, maybe two.
When DNA researchers start actively talking about the tree of life, then we might actually be looking at real designer children. Until then, we are looking at stabbing at something in the dark and seeing what we get.
The term junk DNA is still thrown around, even though it was shown (by a group of people that study language) to be information. From my views, nature doesn't produce junk, everything had an important purpose, or it just wasn't done. Nothing wasted. Since the term junk DNA is still bandied about, we really do not know much about DNA