That's sort of different, since she's a regular Knight available to everyone with the code. Code Girls are only available to the one person with the product.
I think the current Violetta Tulip one is an old one, so if you claimed it before you cannot right now. If you haven't before, here's the codes for her (I believe it's first one listed in her section):
https://harem-battle.club/wiki/Flowe...Violetta-Tulip