Thought I would add an update to this thread.
Heidi is so far from being a feral cat it is laughable. She is an absolute love bug. I pick her up and cuddle with her every day and she accepts it. True, not for a long time but at three years old what can you expect with no socialization? She loves her little enclosure. It is packed with a couple of warm blankets and tons of straw to keep her comfy cozy. She has made herself a little cocoon right in the middle. She gobbles down one, sometimes two, cans of food a day and has gained a smidge of weight which I'm sure she will take off in the spring. I am hoping by then to start her introductions to the other cats so she can be out with them and have company.
Of course we can have a miracle happen and she may find a permanent home too. If not she is home.