Liberty Jackson and the Heroes of Olympus

What if Percy had a sister that no-one knew about, like a twin or something, that went to the other camp even though Poseidon was her dad? And when Percy showed up at Camp Jupiter, she's just like "why on earth is Percy here? He should be in New York." Percy didn't know about her; even Sally thought she'd died, so she'd never told him. Then she goes with the seven because it's her brother and she's not leaving him again and she bonds with Annabeth over how stupid Percy can be and the others give her nicknames like they do with Percy. And after the war, when Percy goes home and takes Anna and her with him, Sally just like faints because her eighteen-year-old daughter that should be dead is right in front of her and the story comes out that Hera took her to the Roman camp to be different, to be raised for her? Then everyone gets really upset at Hera cause not only did she take Percy and Jason's memories, but she took Percy's twin from him at birth and she just regrets everything but it changes the entire series. Warning: lots of violence and some depression.