Just a quick comment about the lawn-watering gentleman, I think he knew Elizabeth, he and his wife both knew Elizabeth. They admitted in a TV interview they were not familiar with Lyric, which seems to point to a gap in time when Lyric and Elizabeth were allowed to be together again. I think when Misty was released from the halfway house that Lyric stayed with Misty in Waterloo as opposed to going to Evansdale on a daily basis and most certainly not when school was in session. I cannot remember when Wylma took custody of Lyric, but I don't think Lyric's visits were on a daily basis.
I agree that Lizzy traveled further on her bike than her parents were aware. IIRC, she even knew the parents of the young woman murdered by her Radiologist boyfriend. They lived close to the lake, I believe, and they knew Lizzy too.
In the video it seems as if Lizzy is leading the way on the bikes. The U-turn on the bikes sounds exactly like kids checking to see if their friends were home. Perhaps, Lizzy had just learned the way to the lake and was eager to show her older cousin, Lyric, but wanted to see if the friends were home so they could ride with them to the lake. When they checked and they weren't home, Lizzy decided to take Lyric to the lake anyway. It seems there might have been some hesitation on Lyric's part because she had just been reprimanded by Dan 2 weeks earlier for wandering off and coming home late. Then, of course, there was the lesson from Aunt Tammy about "stranger danger". I think that lesson was given to Lyric and her daughter, not Lizzy.
It would not be uncommon for children in any small town to wander for a few miles on their bikes and the parents be totally unaware, IMO. Certainly can't blame the parents. No one believes that someone in a small town would be capable of abducting and murdering 2 little girls. Everybody knows everybody, right? I believe Lizzy was quite precocious and made friends easily. I remember reading she even wrote a letter to one of her teachers during the summer. Just by looking at Lyric's smile, she seems she could be introverted, while Lizzy was an extrovert. They balanced each other.
At this point, it doesn't seem anyone can be ruled in or out.... Too many suspects as Sapphire Steel would say. That being said, drugs being involved can't be ruled out either. The person or persons responsible may have been as high as kites when they did abducted the girls. That is where the lines are blurred: Misty, Heather, brother, Aunt Tammy, RSO cousins. It sure has been a long time to keep a secret.
I wonder if the teachers at the day care close to the lake were ever questioned if they ever saw someone unusual at Meyers Lake? Somebody who might have made their hair on the neck stand up... A familiar vehicle they saw regularly cruising/trolling the area maybe.