So, assuming he's telling the truth, he could have called for an ambulance for all of them, including Shanann and Nico, and possibly had to face manslaughter charges, and had a good chance of walking free. But instead he's virtually guaranteed a minimum of 12 years, a likely life sentence, and possible death penalty?
Instead of thinking about where to hide the bodies, maybe he should have just called 911, there would have been less to lose and the medics might have even got there in time to save his children's lives.
ETA hadn't he ever heard of people getting off on manslaughter charges if it was done to potentially save the life of another individual?
Did he actually sit or stand and weigh up the risks of calling 911 to try to save the children vs going on trial for manslaughter vs getting caught hiding the bodies? And all the time the seconds are ticking down for the chance of reviving his daughters?