Just looking at boost/function.hpp, here is the list of authors we need
Could you explain how you did get to this list of authors? I must say I'm quite surprised to be in it. When looking at the various files, it seems to me you are the only copyright holder of all header files in boost/function. So it shouldn't be a problem to switch to the BSL.
Or maybe you are considering that somebody who corrected a small typo at a given time now holds a copyright on these files? I may be wrong but I don't think it is necessary: unless the person did put a "copyright" line in the file, I think the person willingly relinquish its copyright on the trivial modifications. Please correct me if I'm wrong.
It includes a list of all dependencies (files #included by Boost.Function) as well as the Boost.Function files themselves. John