Please forgive my insolence, but you can't have your cake and eat it too. Apparently the dead sea scrolls "failed a test of authenticity." I do not enough on the subject to even begin to attempt to argue that point.
However you state that the dead sea scrolls prove the authenticity of the bible. Here is where we have a problem. If the dead sea scrolls are inauthentic than they can not be used to authenticate the bible. This would be an appropriate comparison: "Harry Potter and the Sorcer's Stone is a work of fiction. The novel Return of the King is mentioned in Harry Potter and the Sorcer's Stone, therefore Return of the King cannot be a work of fiction."
If the dead sea scrolls are authentic enough to validate the bible then they're authentic enough to be included in it.