Assuming the GM will accept it, using Mirror-Sight Dismay backed by 5 motes into the Manipulation excellency to convince the five people in closest earshot (one of whom must be Child) that the belief "The speaker does not know Child's secret" is false.
No, Skandi has no idea what Child's secret is, aside from vaguely suspecting he's an Exalt. Forward momentum!
Actual Dice:
http://invisiblecastle.com/roller/view/3549947/
Specialty Dice:
http://invisiblecastle.com/roller/view/3549950/
Stunt Dice:
http://invisiblecastle.com/roller/view/3549945/