It’s understandable if Numair needs to take a moment to consider what to do with this information, but seriously he can’t refrain from telling them. If he did, he wouldn’t be the good person we have come to see him as.
Hiding his true identity from Hawk is bad, but somehow understandable, especially if read as “I’ll absolutely tell him soon, I just need to have this for a little longer”. Not letting the siblings know about each other would be selfish and cruel. He knows how Hawk suffers from the trauma of losing his family (the nightmare we saw was about the Trade but Numair probably knows something about his other nightmares too with his Seeing) and that Liya thinks she’s lost her family although she seems to be coping reasonably well. I don’t think Numair is selfish and cruel. At least I hope he’s not, even though real people have many different facets to them.
However, as the broadcast is right around the corner (this same night? The “bird” is up) he may choose to not tell until after the big event. Or may even be unable to reach Hawk before it. I don’t remember right now, can they call from world to world or would he have to go to Ardh to speak to Hawk. So, perhaps it all comes to light via some dramatic circumstances (see chapter cover) because of the timing. But he can’t just decide not to say anything to protect his “cover”.
