I agree. Eric made his own informed choice in #1. I don't see a difference between #2 and #3 either. The father has the right to make decisions on behalf of his son. So, the case is essentially the same. I wouldn't charge Peter for murder, as the deaths weren't planned. What else is there ... manslaughter? - Whichever term applies to unintended killing that is not caused by an accident.

As Michael's mum, I'd question Eric's decision to take the kid to a drinking session with his mate though. Divorce impending if they're married.