Conrad and Catherine Snyder had a house in town, but I am unaware of a Snyder farm near Gettysburg. There was a farm of John Slyder, east of the Round Tops. Confederate prisoners who were not wounded were collected together in groups on each of the three main days of the battle and were promptly marched off to Westminster, Maryland. It would be difficult to "keep them down on the farm" after the battle since they would be inclined to escape. Nor does it seem likely that wounded Confederates occupying temporary hospitals around the area would be engaged in repairs, either voluntarily or involuntarily. Now a handful of CSA soldiers did desert and decide to begin a new life in the area; that's the only explanation I can conjure up. I see that Susie was born nearly 30 years after the battle, so perhaps the facts became distorted with the retelling of the event.