i did and i think a half sibling would work out with the parents being dead and kitty being a few years older than ari! all she really knows about her birth parents is they were both purebloods and one of them did a lot of paperwork (like a lot) to shuffle her off to france as a baby and she was never particularly interested in them because she loved the coven she was raised by. i really like the dichotomy ari having a respectful career path while kitty went full tilt into dark wizard, raise the dead, rob some graves, fuck the police (except camille who is perfect) chaos.