Jelinda,
I have a friend who is very knowable on plants. He informed me that your Sans are in the Futura Simplex or Compacta group. Midnight Shine is a rare type slightly different than the Black Futura Goldedge. As I stated before. ID'n Sans is very difficult and I can only give a best guess. It is good to have friends who can help us out. He plans to join our group soon I hope.
They are very beautiful plants no mater what they are. I still would put them all together in a window box setting.
Zig,
When I was in Clearwater Florida, there was wild sans growing around the area and I mistook them for regular Trifasciata. Was wrong (again). I now believe they are Sansevieria hyacinthoides. It is a weed down there and they have a hard time killing it. These guys are very tough. I wish I could have studied them more. See what effects weed killers had on them. I heard you have a similar problem there.
Stush