snipped for focus.
You know, patCee, like others here, I keep oscillating between various scenarios that could explain ED's disappearance. One theory I had temporarily put on hold, is coming back to haunt me. Perhaps like you, I am wondering again about a hitchhike gone bad, in particular at the two 'exit' points on her intended loop. There is the Cabane de la Besurtas where she stayed 21/11 and the Hospice de France where perhaps she hung out 23/11 (or if she successfully hiked at dusk/night, 22/11).
Last night I stumbled on this YouTube video posted by ED and DC - it is brief and it is very happy. But they tell a story of getting 8 (yes, eight!) lifts to return to their van from hundreds of kilometers away where they were hiking that day. Wow! That is very trusting - even for a pair that includes a human male.
And so if on 22/11 ED was struggling emotionally (confused / angry / sad / lonely) or physically (hunger / dehydration / exhaustion / illness / cold) might she have opted to abort her trek and get back to civilization 22/11 or 23/11? And given their / her habitual dependence on others for rides, could she have gotten into the wrong car?