I wish that BD could be made to understand that not only could she help to find her missing daughter, but she could also "potentially" help to clear Shawn if, in fact, he had nothing to do with this whole mess.
All she has to do is tell the truth, the whole truth, and nothing but the truth and give as much information as absolutely possible--including everything she knows about Shawn and his actions, behaviors, likes, dislikes, hangouts, hunting and/or camping grounds, and whether it might be related or not, and most importantly, every single thing surrounding the timeline of when Hailey went missing.
Let law enforcement follow the information she gives them.
If the information turns up nothing, then at least law enforcement will be able to cross those places/things off of their list of things that they need to either follow up on, or do a more thorough search there.
If Shawn is guilty of nothing, then let all of her information prove that out.
I always hate comparing one case to another due to numerous differences in personalities, etc., however, I will say this:
I firmly believe that just as Misty is deemed to be "the key" in the case of finding little HaLeigh Cummings, I firmly believe that Billie is "the key" to finding little Hailey Dunn.
She needs to be a mother and forget about whether or not her bed partner is going to get mad at her for divulging potentially important information that could lead to finding her daughter.
Hailey deserves that much from her.
Tell the truth--if it leads away from Shawn then he/she/they will be vindicated. Deal with the alternative if and when the time comes.
STOP PROTECTING the other adult in this scenario--he can take care of himself.
An innocent CHILD's life is on the line--and she NEEDS her mother's help NOW.