I think I made a major break through with Sansa yesterday. She shares a little cubicle with Robb. The cubicle is in a bank of cubicles containing other cats. She feels most comfortable interacting from inside the cubicle. So, I just go in and open the door. I let Robb run and play in the cat room. He specializes in posturing in front of the other cats who can't get out of their cubicles and then running for the hills. But, Sansa doesn't get out. She plays and lets me pet her inside the cubicle.
Yesterday, she slid out by mistake while playing with a toy inside the cubicle. In the past, when she has found herself outside the cubicle, she's become frantic and disoriented. Yesterday, she got upset, but let me pick her up and put her back inside the cubicle. She was standing up on her hind legs trying to figure out how to get back to her safety zone, but responded to my voice and looked me in the face as I bent down to pick her up.
This may not sound like a lot, but for a feral cat, it's major. The trust it required is enormous. Day by day...Every baby step toward trust makes it that much more likely she'll find a home, hopefully with Robb.