Karen is informed by owl that she's a prefect. She writes her friends about that, of course.
"...well, that explains some things..." says Miranda.
"MY PAPA," hollers Catherine.
"People'll just assume she's a Squib -?"
(Catherine pats her papa's cheek and now he has lemon sauce on it.)
"Yeah. But we don't want her expecting a letter, so we're going to explain as soon as she's old enough to understand -"
"It's vanishingly unlikely. I did check that the birth father wasn't a wizard - so I could duel him, mostly, but also so she'd know -"
"Rebecca didn't want to marry him, but for getting her pregnant in the first place, absolutely."
Rebecca kisses her husband and collects Catherine to napkin lemon sauce off her hand.
"...the official story would have required conduct that would have been very out of character for both of them, so I concluded it was probably a lie, checked that no one involved was presently being unduly pressured somehow, and then decided they'd explain themselves when it suited them?"
"I would personally be upset if people thought I was irresponsible enough to have created such a situation but -"
"It doesn't cost me anything to be thought irresponsible, I'm not angling to rule the world."
"I was a little worried you'd all feel like you'd been - pressured into loving Catherine more than you would've -" says Rebecca.