I don't think whatever permutation of Zanny KC came up with before Caylee's death was necessarily intended to be a scapegoat for the baby's murder/accident, but after using the "imaginanny" to describe to her friends that she apparently had a tony, successful "event planner" job that would require some kind of professional surrogate "mommy" - it was the easiest "out" she could come up with when things hit the fan - or at least after Caylee died.
Many have argued there is reason to believe that Zenaida Gonzales was not simply a name made up on the spot. If the whole ZG22 theory ID pans out (and there is certainly a lot of good analysis that would point to that possibility), that would certainly point to the fact that KC was certainly well practiced in the "premeditation" efforts required to form and use an alias. There are some odd other coincidences that happened regarding the name Zenaida Gonzales that KC could have certainly used to either use to distract or confuse others. One of them of course was the ZG at UCF that had her computer stolen (with all her personal info) the same week the jogger was mugged and killed in JBP (less than a few days before Caylee's own "disappearance"). Another disturbing coincidence was the fact that the ZG who is appears to be the plaintiff in the Morgan case had connections to the tattoo parlor which Casey frequented.
If KC had been using her own ZG22 ID to do things "under the radar", and her own daughter dies, it would make sense to abandon the false ID and see if a "real" Zenaida could be substituted to confuse the case.
I personally think she had other plans for ZG22 initially - ones that may have involved disappearing for awhile and living under an alias while some unfortunate "household weapon" accident occurred and she could inherit her parents house - but something went awry and Caylee was eliminated first - perhaps intentionally, perhaps accidentally.
She may have initially used the term "Zanny the Nanny" as a joke to refer to who really took care of Caylee most of the time - her own mother. I don't know about you, but if I had been CA living with something close to a deadbeat dad and a lazy, spoiled daughter, and the only apparent breadwinner for a family of four, I'd have been medicated.
Maybe she already had her ZG22 identity, so when she told RG that she had found a nanny named Zenaida Gonzales, it was another little mind-game she was playing - as she would be returning home and taking care of Caylee herself until she could convince her parents that the Grunds were just so awful to live with that she HAD to return home. I'm sure both families were told very vivid stories about the others to make sure neither of them ever felt like comparing notes in a friendly way.
Perhaps when she told her friends "Zanny" was late or as a reason for not going somewhere, it was easier for her to say that her "employee" was late rather than the fact that her mother (the real "nanny") was unavailable.
I think the second series of events that will make the jury consider premeditation a reasonable likelihood (even in the absence of actual other evidence) - is the fact that she was constantly stealing. The check-kiting, fake deposit slips, stealing cash out of the house, credit cards, grandparent retirement accounts - all of these acts require careful planning and cover-up - and meet all the requirements of premeditated acts (even if they originated from some other impulse like her pathological lying did).
I don't think we may necessarily be able to prove a "premeditated" use of Zanny as in invention created specifically to cover an equally premeditated murder. I think if ZG was an alias for KC, she was created for a different purpose. But she certainly came in handy when KC needed a scapegoat, even if she had intended on using this alias for a different purpose at a later date.
We may never be able to pry the actual truth of this situation from the evidence that is finally accepted in trial. The jury may not be able to decide from this evidence if Caylee's murder was premeditated (although the time it took to place three or four strips of duct tape on a child's face, covering both mouth and nose certainly is within the accepted parameters of premeditation - even if it was born of impulse initially, the killer certainly had time to reflect on their actions and reverse them.
However, all of KC's other behavior, if she created a previous alter ego, looked for other "ZG"s to be potential suspects, the continuous lying and stealing all point to a predilection for the kind of thinking and behavior that "premeditation" requires - and her elaborate cover-ups she created to avoid responsibility for things she clearly knew were crimes also point to a jury not buying into any kind of insanity defense.
So, even the prosecution cannot prove actual premeditation of the murder or that ZFG was created solely for the purpose of hiding Caylee's death (and I think KC originally invented her for other purposes but she morphed into the "nanny" when it became necessary") - I still think KC's irrefutable engagement in "premeditated" type behavior during this and her other crimes (whether charges were ever made or whether her actual check fraud/forgery trial occurs before her murder trial) will make that irrelevant to the jury. She's done, toasted. Most of her behavior comes across as premeditated - even if it's not well thought out or thought through.
