The scent the dogs picked up, could have been there from a day or even two before. Not to mention (and correct me if I am wrong because I could be, as the "facts" of this case are all OVER the place) but were the dogs not given the other family members scents to rule them out as possibly caring the girls scent, AFTER the dogs had already searched once?
Also what if the dogs simply picked up the scent from the bikes? Being that it was hot, the girls were likely sweaty, so expelling more "smells"....and the girls were not actually there at all, explaining why TG never saw them...or why no one else of creditability (or who we have heard from beyond Tammy saying some random man said he saw the girls)....and why the boy fishing never saw them...
I do personally think the girls were likely there, but just throwing out the above.
I think in a case like this the man who saw them regularly could very well be mistaken what day he actually saw them, add in the pressure of you possibly being one of few witnesses, yikes...could I remember exactly? I am not sure, and I have a good memory!
I think Ollipop had some great ideas, someone local, a car/truck that was commonly by the lake or in the area, so no one called it out as being weird for being there.
I am still not convinced the family or anyone closely (boyfriends, girlfriends) had anything to do with this, even with Dan's case. It's a fairly large stretch to think he would set up the disappearance of his daughter and niece, and if he did. I would think he would just get his girlfriend to take Lyric, let's face (no offense to him) but he is not a criminal mastermind. If he was, he wouldn't be in the current situation he is.
The one thing that repeatedly sticks out about this case, is how incredibly "clean" it is. Every move seems like it was preplanned, every detail accounted for. Not the work of a man about to lose his freedom, not the work of a druggie or someone in that world.
I just cannot think the perps just got incredibly lucky, and got away with this plan with almost no evidence left behind.
JMO