I assume that she didn't meet them in person, because they are filthy Burikis!!!! and no one wanted to expose their precious Sumeragi to them. Except, of course, that she did meet Lulu.
On a related note I meant to say that she comments on his violet eyes so she must have met him in person, but didn't recognize him, which is relevant to this discussion! BUT Lelouch DOES have a tiny flashback when he first sees her in the anime and she's clinging to somebody's leg, so one assumes they did meet in person later.
...so in the long run I say "At the very least she DEFINITELY knows that they existed and would recognize their names, but might not realize they had survived the war, except that she'd know Nunnally is the viceroy of Area 11 at her point in the timeline"
SO DO WHATEVER YOU WANT I GUESS.
Uh hi I'm Kay and I play Lulu (and Orihime and Roxas) and he is... pleased, to... reunite with... this... girl who is the waifu of someone definitely not him.