Stupid, stupid idea...I'm already kicking myself. What if the day that Casey moved out, her parents told her to stay out and do it on her own. then on the day of all those phone calls, there is something that she really wants to do, without Caylee. So she calls her parents to try to get them to take Caylee, they are doing the tough love thing, so they don't answer. So this person, whatever their name may be, sees Casey getting upset, knows the real ZG, knows that she had recently checked out an apartment at Sawgrass. So this person introduces themselves as ZG, and tells Casey where she lives. Leaves, beats Casey to the apartments and picks Caylee up at the bottom of the staircase and takes Caylee.
It would explain a good number of the lies that she has to stick to. SHe wouldn't want anyone to know that she lost her daughter because she left her with someone that she had only known for a few hours.
Sorry, I know that is about to be blown full of holes, but that's what happens when I haven't slept.
This is literally the only thing I can come up with to explain the name if the ZG that LE found is being truthful. Sorry, it's so long.