Hey Jo! Don't worry, I don't bite (unless you ask of course) and super excited to see someone interested in the sister line!
We're not even gungho about what's outlined above, main concern is that the characters fit within the type of family/upbringing briefly described more than anything. (If it helps, Roz and I did take some inspiration from the Bat family for this.) But feel free to throw me an email if you had anything you wanted to run by :D Would love to see the sister in play (ngl, it's the line we were both really hoping someone would take).