This is pure speculation and opinions on my part.:
People saw Casey in jail and heard the words, "31 Days". They saw huge dollar signs so the first thing they do is get JB to represent her with the understanding he cannot tell who hired him other than Casey, imo. He is willing to go along with the 3rd party agreement as it is not illegal for the fees to be paid by another person. He cannot charge more than what is standard for anything he does yada yada yada.
In the meantime, they are busy making other "arrangements" for the rest we have seen come and go in this scenario. Think about the cast of characters aligned with the defense. DC, LG, KFN, MB, Psychic phone girl, JH, and others who have conveniently shown up seemingly out of the blue and offered their services. Then you have the Dream Team, LP (who quickly was out of the situation and went to the other side), and the newest member PMcK, the PI. And we cannot forget GR and how he has access to all of the above anytime he wants them for an interview or film (except for Casey and obviously Cindy!), imo.
It sure sounds orchestrated right down to the smallest factor, doesn't it?