The only reason I could see for Elizabeth's disappearance to be related to the meth trade is if the perp were aiming at Lyric and Elizabeth happened to be there.
That seems so unlikely to me, though. For one thing, if one or both of Lyric's parents were considered a danger by someone in the meth trade, the person they endangered would simply have killed them (Lyric's parent/s). Abducting or killing Lyric would just draw more LE attention to the drug trade rather than less.
One creepy thought I've been having lately is wondering if either Elizabeth or Lyric was being molested by someone outside the family, someone none of the adults in either family would ever suspect. That person arranged with the girl he was molesting to meet at Meyer's Lake and didn't expect both girls to show up. In this theory, the girl he was molesting had become wary, maybe even afraid of this person but he still held power over her. So she went to the meeting as arranged but asked her cousin to come with her, figuring that nothing bad would happen in front of a witness.
What makes me think that this theory is less likely is the level of planning that would have gone into such a meeting. Most of the time, perps who kill their child victims do so on the spur of the moment out of fear. For such a perp to arrange a meeting, etc, would mean risking his victim would tell an adult before the meeting.
The main problem I have with any theory connecting some adult member of the families to the perp is that the perp had to then successfully buffalo LE. I'm sure that all the adults in the family (and all the children) have been asked if they know anyone who might abduct the girls, anyone who had a reason to be angry with them, anyone who gave them a strange feeling, etc.
Anyone LE questioned had to cover up a sizable hole in their day on 13 July.
