I watched the People Magazine Investigates show on ID last night about this case. I wanted it all laid out in a straight line in an easy format. (It was late!) I have never had a firm opinion one way or the other on who or when baby Deorr disappeared.
My thoughts: Grandpa is clueless due to his severe lung problems. I am an RN and when you are always struggling to maintain a liveable O2 level, your level of awareness is very poor. You can fall asleep while talking, your memories are blank. You are very in the moment.
I believe DeOrr's parents gave him something to sleep that night so he would sleep hard, as the family (3) slept in a vehicle together. What the parents were doing is unknown, but they probably didn't want the baby to wake up. The next morning, baby DeOrr is dead. That's where all the weird stories about who cooked and did what started. I think the parents left the body in the car, made an appearance at breakfast, and left for the store for what they said they needed.
On the show, the police said the family spent an inordinate amount of time in Leadore, a town with about 25 homes. I think during this time, the body was dropped off around Leadore or within reasonable driving distance to get them back to the camp.
Knowing Grandpa as Jessica did, they played that Grandpa had seen him and was watching him. (Grandpa has no clue, bless his heart.) They fished for a while as planned, then one by one went back to raise the alarm and start the search.
Baby DeOrr was not found in the camping area/state park area because he was disposed of outside Leadore somewhere.
FWIW, that's my take.