JMO but I feel that's there's absolutely no way that Logan could have sustained those injuries - and if still awake and cognizant - not be crying out or screaming in pain. If AW is going to claim that she didn't know, or was unaware, of his injuries, I can only think that he was unconscious (had maybe passed out because of the pain or was knocked unconscious by JC) and AW just thought that he was sleeping.
Also, to echo the thoughts of someone who commented earlier, I too believe that the 13yr old's involvement is that he assisted in carrying Logan's body to the river, and it was this act that was captured on the doorbell-cam footage and thus incriminated him.
Maybe the 13yr old PTCOJ by doing that, and maybe AW PTCOJ by concocting a half baked story about Logan going missing and the door being open etc. Perhaps she was planning the 'cover story' whilst JC and the 13yr old were out disposing of Logan's body in the river, and JC said she better think of a plan by the time they get back?
All just my opinion.