I have a theory.
As previously stated, I think this family is incredibly dysfunctional. Effective communication between them is nonexistent. However, I do not think CP and SP intentionally did anything to Erica. I think that, in the end, those who are wanting blood from them will be proven wrong. I think they made mistakes, but nothing as bad as what people think.
However, I am losing hope for Erica. I think the earlier quote about human trafficking kind of takes the wind out of my optimistic sails. The Parsons went on national freaking TV and gave a wild story about Nan. However, the details of there story should be examined. They said that they were contacted by Nan's crowd, and they knew everything about the Parsons. These folks got a couple of weekend visits with Erica, treated her well, then convinced her to come with them for a longer period of time. Gave her lots of things, made her feel special. They gave her the attention she could not get in the crowded home.