Kasius the son might have said something off screen since he never liked his brother.

Or Daisy got a hold of someone’s script and read it herself. Hahaha

my question was about the character's knowledge; not the actor's/actress's. the actor/actress knowing something is not necessarily the same as the character knowing it.

Kasias commenting about it off screen might be likely.

script reading would be how Chloe (her actress) would know.

The second part was a joke, of course.