I think there are varying theories on that, I think several believe Crystal does know where HaLeigh is now and who has her, I believe that as well, JMO.
What is the theory you've attached to the belief? I mean, how did Crystal arrange it? There were several things she had to do in order to assure getting HaLeigh out of there so successfully. The way I've attempted to make it work for Crystal to have arranged it takes too many chances, with too many variables put into play by Ronald, Misty, TN, and even GGM.
IF Crystal did it, for instance....She or her agent would have to have waited somewhere nearby. As we've all seen, there are woods all around, but people live in a lot of those woods. She or her agent COULD have found a spot (I'm guessing the twig chair would be a likely theoretical spy spot). HaLeigh comes home from school, loves on her daddy's neck, tells him she'll see him when he gets home, and Ronald leaves the playing field. Then, Misty is there with the two children and her brother and his children and maybe/maybe not her cousin. By 5:45, they're off the playing field as well. Misty is there with the two kids, and we can assume she is occupying herself with the domestic chores everyone has at that time of the evening. Preparing dinner, cleaning up from the guests, what have you. At sometime between 7 and 8, GGM shows up and hands Misty clothing to take into the house, views the children on the porch eating dinner (she also discusses in one of her videos being in the house and seeing HaLeigh playing and how distraught she is now that HaLeigh is gone that that's her last image of HaLeigh......gotta find that video again). So anyway, GGM finally leaves and she's off the playing field.
Now it is just Misty, the kids, and Crystal and/or her agent, sitting in that chair waiting and watching. Kids go to bed at 8-8:30, but not to sleep. They're watching movies in two separate rooms. Misty's location in the MH is never given. Was she doing the laundry, cleaning the kitchen? I don't know. Some say the 911 tape says she was cleaning. Her statements later says she was doing the blankets because the kids were down and HaLeigh didn't have a clean blanket. By 10-10:30, Misty herself lays down.
The stage is set for the watcher-in-the-woods (Crystal and/or her agent). The back door is locked (INSISTED UPON by both Ronald and Misty, acknowledged by TN and GGM). The front door's locked/unlocked status is never discussed. The back door, visible with no obstruction in an open yard and a vast expanse of grass with no trees on it is the preferred entry point to the watcher. Not the covered front porch which would at least provide cover while ingress takes place. The back door, up a creaky looking ramp, opening an equally creaky screen door, which is propped open with a cinder block presumably found by a pile of cinder blocks in the yard....at what time? Then? More time exposed in the open with the risk of being seen...anyway. Entry is made. Immediately they're met with laundry piled on the floor (confirmed by TN during her video walkthrough), and Crystal and/or her agent walk over those piles and turn on the kitchen light situated at the opposite end of the kitchen from the back door entry. Again, a light would blow the cover of secrecy an abduction would seem to warrant, but then Crystal and/or her agent is operating on an obvious agenda of attaining custody illegally, so......moving on.
Leaving the kitchen, light on and shining onto the floor into the living room, Crystal and/or her agent must make a decision about where the kids are. They're not in their rooms (INSISTED UPON by Ronald and Misty, acknowledged by TN and GGM) but instead are in the master bedroom. So now, Crystal and/or her agent, having exposed herself/the agent in the treeless yard to go into the exposed back door via lock bumping, stumbling over laundry and fumbling in the dark to find a light switch in a house she/the agent has never been in before, having looked in bedrooms for the children, realize their prey is in the master bedroom with the only other near-adult.....Misty. HaLeigh is sleeping right by the opened door. Misty is about 3 feet away on the big mattresses, Jr by her side. Crystal and/or her agent must make a choice now. Take HaLeigh (easiest) and leave Jr, or back out of the whole mess and hope she/the agent has not been seen and rethink the whole dang thing. Well, obviously, Crystal and/or her agent has thought that HaLeigh is better than nothing and grabs her. She made no noise, Crystal and/or her agent made no noise, and Crystal and/or her agent and HaLeigh head BACK out of the master bedroom, into the living room, through to the kitchen, stumbling through the laundry on the floor, through the back door which didn't quite latch when they entered, past the blocked open screen door, down the crickety ramp and back into the woods, past the spy chair and presumably to a waiting car, and off Crystal and/or her agent go with HaLeigh.
Now Crystal sits, the grieving mother, but not really....being watched constantly by everyone, judged by most, and unable to see her little girl she's just risked EVERYTHING to steal out of her bed.
That's where it all falls apart for me. To go through all that work to take her child, to have exposed herself and/or another person to the risks involved in EVERY LAST STEP OF THIS scenario, only to not benefit the joy of having HaLeigh????
Logic suggests that it must be discarded because in order for Crystal and/or her agent to have gotten into the house given the outline that Ronald and Misty have assured us is the only way they could have gotten her.....it can not have happened.