After reading through Dad's entire declaration, I'm utterly heartbroken for this family. What a mess. I agree with what others have said. I see no deception from the father. In fact, it looked like he was doing everything he could, and the system failed him, and the children. In a way, it also failed Julia, I suppose.
A side note: I have a hard time imagining, if Julia and the children lived with her mother through some of this, that Julia's mother had no idea how sick Julia really was. Yet she went along with Julia, it seems? Cindy Anthony anyone?
Anyway, to me, it seems equally as likely that either poor Sky died as a result of being neglected (either as result of an accident during the marathon mediation, or through lack of care, possibly through some illness in the last week) OR, after the mediation went in a way Julia didn't like, she felt the complulsion to do something drastic to 'get even' with the father.
I also think that's why Dad's polygraph was inconclusive. I think deep down he 'knows' Sky is dead. Doesn't know how or where or when. He just knows.