Spread margarine onto one side of each slice of bread. Set a large frypan over low heat, and lay 6 bread slices in it with the butter side down. If you can't fit 6, just fry in batches of 3.
Place slices of cheese onto the bread in the frypan and let cook until the cheese starts to melt. Place slices of corned beef and chicken over the cheese and then sauerkraut. Spread the creamy dressing onto the dry sides of the remaining slices of bread. Place dressing side down onto the sandwiches.
Increase the heat to medium and cook until browned on the bottom. Turn sandwiches over and cook until golden on the other side.