Casey's parents had been told that "Zannie" was the nanny for awhile, right?
IMO
Zannie the Nanny, was Xanax,(also known as "Zannie's")
IMO
Casey may have gotten great satisfaction from telling the parents Caylee was with "Zannie the Nanny", in the past, because they didn't get it, and thought Znnie was an actual person.
IMO
As Caylee became more of a handful, (Terrible twos), she may have used her chemical nanny more often.
IMO
One one of those occasions, Caylee OD'd.
Initially, Casey panicked, but as she thought it through, she saw it as a blessing, and just had to figure out how to get away with it, with her reputation intact.
IMO
She may have disposed of Caylee's body early on, and had to keep making excuses as to where her baby was, until she could figure it all out.
IMO
Casey went to Sawgrass hoping to get an apt. close to Tony's (either too squat in, or live in), and came across a person named Zaneida.
She never spoke w/her, but the name stuck in her head.
IMO
Casey was too busy compulsively living her fantasy life to think of a plan that would work.
She'd abandoned the car, but could still get around..there was no urgency to figure a way out.
She kept putting it off--she was having too much fun.
Besides, it was all okay, her parents were buying her excuses still.
Why not have fun?
IMO
Casey's doormat mom, did something uncharacteristic: she challenged Casey, and Casey had to scramble. She remembered the name Zaneida, and used it when her mom pressed her about going to Zannie's to see Caylee.
That's where Zaneida as Zannie was born and she ran with it.
Again, all my opinion, but i'm curious as to what y'all think.
I live here in central fla, so all I think about is this case.