Every time I consider a theory like SODDI I keep coming back to KC. When she found Caylee missing, if she had nothing to do with her child becoming a missing child why wouldn't she call 911? Esp. if she had been stalked previously.
Another question I would have is if SODDI then why would KC make up the Nanny, the two stories about Sawgrass and the park? Esp. if she had a sense of it being someone else? And why wouldn't she have a better, more complete story of how Caylee came to be missing? IOW if SODDI why has she consistently protected them?
Looking at KC's personality traits, KC appears to get frustrated easily and to anger easily. When angry she doesn't seem to remember what would be best for herself, let alone what might be best for someone else. So if her child came up missing, I can't see KC sitting down and thinking "well if I tell someone, then the unsub might get angry and retaliate." And even if she did think that, then when Caylee was found dead would have been a prime time to tell LE the truth, because the alleged perp didn't have any more leverage to harm.
The closest I am come to SODDI is if KC's boyfriend harmed Caylee and she was trying to protect him. But if that was so I would think that story would break down when she got charged with murder herself, and he broke off contact with her. I mean her daughter is dead, she is charged with murder and looking at the death penalty, and he isn't dancing attendance??? Sorry but I don't believe she is that altrustic.