Two different ideas on Joker's Daughter:
1. A small cute child with blond pigtails wearing a pretty white church dress who after attending church with her family grabbed a butcher knife and murdered her family, when the police made their way into the home they came upon her with an eerie red smile painted on face, which one cop said that it reminded him of The Joker, with her mother's blood and saying that she did something very naughty while giggling a small child's laughter.
2. An alternate take on Duela Dent/Joker's Daughter/Riddler's Daughter...etc: A girl with split personalities who is committed to Arkham Asylum for a night but ends up meeting many characters and after each character leaves an effect or an impression on her it leads to another personality that thinks they are the daughter of the character.
Personalities/Characters includes: Duela Dent, Jess Terr, Veruca Cobblepot, Amber Lynns, Jane Wayne, Prudence Crane, Megina Nashton, Batul al-Ghul, Yolanda Jones, Alice Tetch
Gunbunny/Pistolera - A western loving gun expert who tries to get Batman to use a gun to start their "showdown"
Ruby "Ryder" - An older rich woman who knows of Catwoman's past (maybe her mother or step-mother) and tries to flirt with Batman in front of her.