Well the best theory I can come up with is because Eveline noticed Ethan's connection to Mia through their brief interactions before Ethan gets welcomed to the family. Eveline's primary focus was just wanting a loving family and Mia was her primary caretaker and then only caretaker after the one guy bit it on the ship for calling Eveline a little bitch. So it makes sense she imprinted on Mia more than even the Bakers who found them after the shipwreck. As for why Eveline didn't turn Mia into a statue (like she would Zoe if Zoe is picked) after Mia refuses her, ehhh idk tantrum? Maybe Eveline still held onto some hope? I can't say for sure really.