Spot on. They know more than anyone else, apart from BL. They are 100% involved and their silence says so.Their behavior isn't consistent with not knowing what the hell is going on.
If he lied to them, perhaps saying Gabby left him, and that's why he's home without her, then 1, why did he have the van, and 2, why didn't they respond to Gabby's mom's calls? They would have been none the wiser and answered. IMO, they knew from the beginning. They pushed the sister out, so she's not implicated. They came up with a plan that included a 3-day camping ruse. They came up with a way to make it appear he left later to give him a headstart, hence the car parked at the reserve and now the extensive and very expensive searching. They met with their lawyer the minute he was charged with something. Now, they're walking around with poker faces.
I don’t know why LE is so heavily focused on the reserve. I imagine they are going on more than just BL’s parents’ word.
Part of me believes BL is not in the reserve and that his parents bought him time by not reporting him “missing” for three days. The other part of me wonders what LE knows and why they continue to search the reserve extensively even after reporting that nothing has been found.