She wouldn't keep her nature a secret from him, especially as it relates to what might happen if she got seriously wounded and he tried to "help" with conventional healing. And it's not unreasonable to assume he would have been around to see her sometimes grit her teeth in the presence of blood. (oh, but her own blood - meh)
Newer company... I liked Atma's reaction before, and I'm tempted to say that their kind would have a sense for each other, but Mandy would certainly need to know before she makes the same mistake as above. So it would be better for them to be in on the secret earlier same as with Mihaly.
Atma and Mandy are in the spotlight, so we *could* say that their actions in the public eye have reached our spheres. An test demonstration for miracle tech, also gone horribly wrong, is something I expect we've all heard about. I think the true enigma in the group is Lastolva.