They're now asking for anyone who was even AT the lake that day to come forward and speak with police - if they were there for any reason at all -- then they asked for anyone who was fishing etc to come forward -- I think they have other witnesses who have come forward who have told them still about others they saw there that day, or who reported they knew someone who was going to go there that day etc -- and those are the ones they need to hear from. I wonder if maybe there was an ice cream truck at the lake that afternoon? Perhaps the kids dropped their bikes and ran because they heard it's tune and were snatched like that? I don't know of course -- just purely speculative, but its possible. They're saying people may not think whatever they saw is relevant because they didn't see the kids -- but it could be completely relevant!
This makes me think they may think that someone set some sort of trap - something to lure kids, and when they found their victims, they made off with them. I've often heard it said that sometimes the best cover is in plain sight. Perhaps they're looking for someone who was cutting the lawn that day, someone who was playing sports at the park there that day, someone who was fishing might have approached the kids -- someone in plain sight who no one would think of as looking out of place or suspicious!
I think they know something, but they need more info to tie it together. Maybe more info to confront a POI with? I am not sure -- but I bet someone was right there, in plain sight, and acted like he knew the kids, or something and just lured them away.
Also, I noticed, they are still focused on the lake area. They're not asking for people to come forward from the other parts of town (around Lederman's for instance). They want people who were at the lake -- so they must now think the kids actually did make it to the lake, and were riding that trail when something happened.