I don't have anything to add to what you already know.
None of this is news, but investigative work done for the show adds significant depth to what we already know.
They cleared up perhaps ten more words by the end of the after- noon which added nothing to what we already know.
I can't add anything to what you know, and neither can my father.
I ask him if there's anything he wants to add to what we know.
Something he's worn or held to really see him, to add to what you already know.
Two other recent releases are worthy of note, even though neither adds to what we already know.
He said he wanted us to have them; they add to what we know of her sad life.
Nothing new for me to add to what we already know.
I have very little to add to what you already know.