Reading the DCF report, I'm certain that someone had visions of themselves as a 'savior' of this baby. Whether Shannon needed it or not. Maybe she did, maybe she didn't, but someone thought she did and I think that's the most important thing in terms of the case. She ends up going missing and there happens to be a woman accused of abuse and potentially murder involved pretty closely with the family. My theory is that Shannon is alive and the abductee of a woman who might (inaccurately or not) feel like she was railroaded by the system and wants to "save" a child from an uncertain fate. Or perhaps she feels terrible guilt for what she did and in her troubled mind things she can make things right by "rescuing" an "abused" child/reclaiming what she has lost. Either way, in my theory Shannon's alive and that's why I'm sticking to it. Maybe they have a POI, but no means to locate her? It's certainly complex when you factor in the lack of Amber Alert and the initial statements that the mother was admitting to things.