What I think is so significant about the GJ, is that a person cannot be compelled to present testimony that would tend to incriminate themselves. That is why KC did not have to appear.
There are 4 members of that family that were most involved. KC of course did not appear. George did appear. To me, it is significant that Cindy and Lee were not called. We know that Cindy made the 911 call, she possibly handled significant evidence, she made several statements about what her dau said to her. But she didn't get called to the GJ? Is it for the same reason that KC didn't get called?
LA also did not get called to the GJ. He was there with KC and Cindy the night this all blew up. He had private discussions with KC, he also handled possible significant evidence when he picked up KC's belongings. And he didn't get called to the GJ?
This could just be part of the prosecution strategy. But really, I wonder if it isn't more than that!