I don’t know if this has a novel or something that provides the full background story. So far, following only what’s shown in the manga, her parents claimed she was a fake because her sister awakened her powers and in each generation of the family there is supposed to be only one heir that inherits the powers. So they titled her as fake because her sister had her powers first.

Please, can someone spoil me about Richette's true parents ?
Is she trully a "fake" ( being swapped at birth ) or her 'parents' just claimed her as fake because her magic came late ?