In the previous thread, someone mentioned that AW couldn't testify to anything that happened at any of the murder scenes because it would be hearsay since she wasn't there. I don't believe that's entirely accurate.
Since it's GW4's trial, she couldn't testify as to anything BW and JW told her that GW4 did at the crime scenes--that would be hearsay. However, if GW4 directly told AW from his own lips something that he did, it wouldn't be hearsay. Example, if GW4 directly said to AW, "I tried to fire the first shot but I couldn't see over the oil filter suppressor." I'm pretty sure that's not hearsay since AW is stating something that GW4 said directly to her about his actions during the crimes. JMO
As for there being no physical evidence GW4 was at any of the crime scenes yet, I think it is coming. I think AW can testify about several things regarding the shoe prints that will confirm which Athletic Works shoe prints are GW4's even though she wasn't there, thus proving GW4 was in fact present during the murders. She can verify in her testimony, not using hearsay:
What shoes she bought for JW
What shoes she bought for GW4
Whether she bought any footwear for BW
Whether JW and GW4 were wearing those shoes when they left the Peterson Road house on the way to the murder scenes
What shoes BW was wearing when he left to go to the murder scenes
What BW's normal shoe size is and whether BW's feet would fit into either pair of the Athletic Works tennis shoes she bought
What shoes those three had on when they returned home and whether she saw the "murder shoes" burned
In addition, JW can also testify as to which shoes GW4 wore while at the murder scenes
I really think JW and AW will hammer home the validity of the shoe print evidence for GW4, but time will tell.
All JMO