I used to have a mapkey in sheetmetal 2001 to produce a flat patteren of a part as an instance ensuring that the unbend was the last featurn in the flat pattern instance.
Where is this in Wildfire 2?, Flat pattern just flattens the part in the generic.
Using Ben's method (which should be the defacto way), the unbend will always be set at the bottom of the Model Tree. You will need to recreate your mapkey if you want to use it still.