My theory:
In my opinion, BS is the main suspect. I believe he and possibly AJ are the ones who abducted William.
BS knew the children would be at the home (due to his interaction with the grandmother) and he and AJ watched, waited and kidnapped William because an opportunity presented itself.
PB and DN possibly had access to William after he was abducted, or know what happened to him. They may have exchanged photos or videos of him, or helped distribute him to other members of this apparent paedophile ring.
These men are covering for one another, because if one goes down in the William case, they all will. They will all most likely face different charges, but they will all be charged with a serious crime in regards to William.
The police probably realised early in the investigation that the likes of AJ and PB and DN frequented BS's Pawn store (who knows what was seized in the raid - computers, receipts, documents, etc), not to mention the other connections such as AJ once living across the road from BS and PB being "very close friends" with AJ.
Even if some of the POI did not kidnap William, I'm sure they have broken the law in some way. Receiving or sharing a photo, withholding information. There are probably many POI we are unaware of yet, but I'm quite certain they will be linked to BS, PB or AJ in some way. Through friendship, business or community groups.
The abduction of William was due to a blatant and possibly large paedophile ring. Expose this, Jubelin. Find William and EXPOSE this evil.