Looking at the perspectives of the past while creating new perspectives - surely this must be basic to any kind of biographical/historical novel? I do not think that it is possible to avoid the addition of new perspectives. As soon as a writer decides to mention one particular event or one particular character instead of another event or character, his/her perspective is already colouring the perspectives that are already embedded in the actual historical narrative. The different types of perspective and the pull between them is something peculiar to this type of writing; fiction writing is not necessarily beholden to any kind of embedded perspectives as it relies almost completely on the perspective of the author.