Even if, and it's IMO a highly unlikely if, they exclude CA's statement about it smelling like a dead body in the car, there's still the tape of GA's interview with YM where he says "You never forget that smell once you've smelled it!" Not that GA's nose is calibrated, but as a former law enforcement officer who has smelled the odor of human decomposition before, I'm positive that statement will be allowed.
Of course, the issue of "31 days" will be easy to prove, with or without CA's call, and the photos of the tattoo are already in evidence. Personally, I think they're just grasping at straws hoping for something to get them a reversal on appeal, and IMO they're challenging the wrong evidence. I'm no lawyer, but I can't see it being productive to go after evidence that can be proven through other means.
The pre-disappearance photos are meaningless to the prosecution, and if the judge issues an order to not allow any pre-disappearance photos into evidence, the defense is cutting off their own nose. One would think they would WANT pre-disappearance photos allowed into evidence, showing the doting Mother of the Year!
Just my .03 here. I've been wrong before