For several reasons, I can't agree that the defense counsel conspired w/ KC to write these letters.
1) these letters start being penned very early in KC's incarceration - I hesitate to even estimate a time because I am on phone call overload and I know the calls confirming verbal communication between KC/RA began even before Caylee's body was discovered. However, I can recall in one of the letters KC expressing her disdain in re. the one time CA didn't show up to a hearing and I
know that happened long ago. During that time, JB was her only counsel. Sorry, but I don't think he is even close to being savvy enough to concoct a plan like that. Plus, during the early stages, I believe the defense thought they had several options - evident by all the people who have tire-tracks down their backs right now.
2) KC possibly incriminated JB by bragging in writing about the letters he was willing to smuggle in from her parents.
3) in re. KC's additional Zanny (that is the way I spell it

) story - I have listened to the RA calls ad nauseum and I can tell you the one thing you get from every.single.call is how much RA loves and misses her kids. That part is sincere. I think KC did what she does best and played on that. 'Poor me..my mom is a b**ch...I
had to get out of that place...so, I left her with Zanny while I planned my escape & saved $...Poor me, when I went back to get Caylee, Zanny was not to be found. Then she switches to martyr status and can't blame Zanny for not wanting to show her face and insert herself in this case....she is the ultimate Christian and chooses to forgive her. I don't think RA bought it, but I think KC thought she did. All of this is just typical KC to me.
There are other reasons, but those are the ones that come to mind immediately.