
If I'm remembering correctly
Mc is the real daughter, Swan never was the real daughter. The mother had the power of foresight and knew that Mc would be kidnapped.
This is the part I'm too sure on
Either the mother put her powers in the necklace and knew Swan would be the 1st one to touch it and be the "fake" for Mc to grow up safe
Or
She didn't know Swan would be the 1st one to touch the necklace. Since her powers and memories? Would protect Mc until a certain point and hopefully by then the father would have found her already.
The necklace had some kind of holy power and a kind of imprint. Since Swan was the first one to touch it as a infant. It imprinted on Swan, extending her lifespan & changing her looks. So Swan never was the real daughter, a decoy made by mistake
Iirc, the holy power inside the necklace imprint on Swan because she's weaker than Lilyan. The power goes to the weakest living thing in the room.
Swan became a decoy to trick fate, because both Lilyan and her mother were a saint(?)- I forgot the terminology they use- whom always have a short and sad life.
She reminds me of a qoute
"No matter how bright a torch may burn it will never match the rising sun"