Okay so this is interesting. The general consensus is that Holly=Rowan=Willow yeah? So here's the thing about that.... Rowan was with Haley when she accidentally answered the test call that was apparently made by Willow which kind of kills the idea that they are all the same person.

We also now know that Willow is candidate alpha but used to be candidate c. So I present to you this

Holly was candidate A but failed stage 2. Rowan would have been candidate B but failed leaving Willow who was Candidate C as the new candidate A.

That being said there's a lot of questions that I don't know the answers to. If Holly Rowan and Willow are all identical in appearance why are the others not? Holly's Naomi was a woman with 3 kids and a husband, Rowan's Naomi was a 12 year old child and Willow's Naomi is back to being a fully grown woman. Rowan's Oliver was an old man but neither of the other Oliver were described as being particularly old.