I'm stuck on a couple of timeline details that might be significant.
MG said in the interview that she visited Lori over a weekend beginning September 19th. That was a Thursday and is the same day that Chad flew to Phoenix and told a felow passenger he was going to help a relative remodel. MG flew home on the 23rd I think, or possibly the 22nd.
MG reports that she, Lori, and Chad walked the track at BYI-I. The only days they could have done that were Friday the 20th or Saturday the 21st. If Chad were in Rexburg on Sunday the 22nd he almost certainly would have been expected to be in church and spending the rest of the day with family, right?
We don't know how long Chad stayed in Phoenix but it would be very strange to fly on a Thursday and not stay through the weekend. I'm not sure I buy the remodeling story but regardless of what his business was I would think he would stay a couple of days, to get a cheaper ticket if for no other reason.
So that makes me think that Melanie is mistaken on which weekend she was in Rexburg. I think she was there the weekend before, September 12-15 or 16. I would also note that there were 2 podcasts in September, one on the 7th and one on the 16th. The one on the 16th was CD,LV, and MG. The earlier one was just MG and LV. I don't think LV or MG have the tech skills to produce a podcast. I think the one on the 7th was prerecorded in Phoenix before LV moved with help of JM and the one on the 16 was produced during MG visit to Rexburg with CD help.
If MG is mistaken about the weekend she visited then that means another friend visited on the 19th. And whoever that was islikely the last to see JJ alive, and could very well have been brought in to assist with the "wet work." Chad may even have made a day trip to pickup this mystery person.