Misunderstood (Mal's Twin Sister)

What if mal had a twin sister named Sophia who wasn't evil at all. When Maleficent was around she would pretend to be evil but once she goes to Auradon she can get away from Maleficent and be as good as she wants. What happens when she finds out she is a princess. Why would Maleficent have her then? Because she stole her as revenge for putting them on the isle. She hates the fact that she has more power then Mal and threats her as the favorite because she has more power. But what will happen when Mal finds out that they aren't twins? This will all be discovered in my story.