I would think SO will not testify. Instead, she gave a sworn statement to an officer or officers (probably plural).
That statement can be read or summarized by the person to whom it was sworn or by a lead investigator. In that manner, one LE witness can give evidence from various witnesses or crime scenes. It sure sounds like the DA has reorganized from 18 witnesses to 8, but I bet the sheer amount of information will still be comparable, it's just more efficient this way.
In this way, the DA can ask the LE witness to simply say how the story began, what brought the situation to LE's attention, what happened next, who called them, and so on - and why they decided the house was a crime scene. I suspect that they have two people working on the physical evidence as lead people (perhaps one CBI, one FBI), and each will summarize what their whole team found.
We will certainly begin hearing actual names of the various participants, though - the people who in fact may be called as witnesses for trial. I think SO, CC and GD (and maybe GD's spouse) will be mentioned, along with MM (the sister), and the two daughters. Seems that something said by MG is going to be in there.
It just occurred to me why Barry put the bike there. He knew there would be a welfare check, but he didn't want them going inside the house, so he led the neighbor to find that Suzanne's bike was gone and then to find Suzanne's bike (the neighbor walked around after seeing that Suzanne's bike was gone - presumably the neighbor had a way to open the garage door, perhaps it was never locked).
But did the original responding officer enter the house anyway, as is common on a welfare check, especially when a person could have been injured in a bike accident or even had a medical emergency causing the bike accident...and then gone home?
I bet the daughters gave permission to enter the house. Barry avoids talking directly to LE on the phone (for the most part). Was there a key hidden somewhere that the officer could use? Do officers carry equipment to jimmy doors on welfare checks? At any rate, I am sure someone called for a welfare check and someone in the family gave permission to enter.
So, when the officer entered the house...was he immediately overwhelmed by the smell of bleach?
Barry wouldn't be home for another 3 hours.
I wonder when that first search warrant was issued.