Why are you so hung up on DNA? I didn't even mention it! Here is what I said again:
Although botanical life is completely different from animal life, the definition of "organism" remains the same. In the case of apples, they are never self-replicating organisms, they are produced by the organism which is the tree. If the apple falls off the tree, it dies. The seeds within the apple may lie dormant for years, until a process we call "germination" happens, and the moment those cells begin to grow through the process of germination, a new organism begins. There is no requirement for the organism to grow into a great apple tree and produce apples, the process of life was carried on, regardless of how briefly that may have been, and it defies science to conclude otherwise, because inorganic material can't reproduce.
DNA does not define whether something is a living organism, it is merely a blueprint of the organism. I have an analogous story to illustrate how stupid your point is here.... A man has been admitted to the local hospital with all kinds of life-threatening symptoms. The nurse checks on him to find him unconscious and not breathing. She quickly grabs a doctor; "Doc, come quick, I think my patient is dead!" The doctor comes into the room (Dr. Apple) He doesn't examine the patient, he simply looks at the patient's medical chart, and says... "This man is clearly dead!" You see, the doctor ignored biology and science, he didn't bother checking for a pulse or heartbeat, he only looked at the patient's chart, and made his determination based on that alone. Do you see the idiocy here? Because this is what you are saying, it doesn't matter if the criteria is met for an organism, all that matters is the DNA can't show it is alive.
Now, here is what DNA can tell us, since you are so hung up on it. Whenever that successful fertilization happened and the fertilized cell generated another cell, we can examine the specific DNA from that produced cell, and it is different than the DNA from the host. This leaves two possibilities, the woman is a chimera, or a new organism has began. Since we know that chimeras can't produce DNA, they are either born with two sets or not... we can reasonably conclude this new DNA is not the result of the woman being a chimera. The only other possibility is, she is pregnant with another living organism. The reproduction of a cell confirms it is a living organism, DNA confirms it is another human, other than the mother.
An organism has to be able to carry on the process of life. If a cell was reproduced, it did that. There is no time requirement or threshold which has to be maintained, it merely has to reproduce one cell, to be considered a living organism. It may STOP being a living organism at any time, maybe even after it produced just one cell, but that will never change the fact that it met the criteria, and for that moment, was a living organism.