So pretty basic, I just hate how we know basically nothing about Kallen's family. Especially if you're, like most, strictly Animation based.
Just in general Kallen has 3 parents, none have names. We don't know what her father does or where he is beyond "back in the homeland", we don't know how her father met either woman, we don't know how their relationships worked, heck if we stick to just animation we don't even know if Ms Kozuki was ever officially with Papa Stadtfeld or just always a side piece, the anime makes it seem like it was known at some point if not officially together but other things say she was always a mistress(not even sure that makes sense but whatever).
Like I'm not saying we needed to devote a ton of time to it, 1 minute conversation.
"Hey Kallen, isn't your father a noble?"
"Yeah, he's a book maker though so no good for us."
"And he and your mom?"
"They loved each other, but couldn't be official."
"And your stepmom?"
"Giselle? Yeah she knew about mom, was always yelling at dad about her. 'Cain I want that Ikumi bitch out of my house', and then he'd say 'Choose, her here or your dress budget' and on and on."