I know that every bit of knowledge helps, but at this point, weeks later, we still know so little. We don't know how the bikes came to be where they are, or the purse, or even where the girls really went that morning. And we are not likely to be told, if any of this info is even known.
All that can be done, IMO, is try to figure out where they are NOW. If a local, stranger or otherwise, took the girls, he/she/they probably did not "keep" them for long. If not drug-related, this is a sexual case, IMO. Generally the victims are found not too far from where they were taken, within several miles anyway.
Have locals seen helicopters being used? Is LE making appeals for farmers and landowners to walk their properties, check their outbuilding, etc.? Did LE talk about thinking back to that Friday, was anyone not at work who should have been, anyone washing out vehicles that weekend, anyone sell a car or truck suddenly? Is there a local "oddball" who has an interest in children?
I know LE said initially they believed the girls were alive; but I did not get the same feeling in their final PC. At first I thought maybe they halted the PC's to placate a suspect and that we would see a swat team surrounding a house within a day or so. But that didn't happen. I wonder if LE had a working theory that has not panned out and are back to square one again.