I think its really nice that you asked them, and they are probably just too distressed to answer right now. I think sending a with sympathy card or similar would be nice. I had wished I had that when I had the miscarriage, it would have acknowledge the baby as existing. (they may or may it like it... But whichever way you are trying to be considerate, and that will be appreciated when they can). Maybe the first time you see them you try to do a grown up catch up without the kidlets if possible?? That gives them the chance to see you which is like a stepping stone, and they can see the baby later.... It's like an anxiety hierarchy sort of... Progressive exposure to the stressor is easier than flooding it all at once.

Even if they are sad for themselves, they ill still rationally be happy for you x