If you have unpublished photographs taken by a deceased
relative which you
wish to use on Wikipedia, how would you license them? Assuming that you
have survivor rights or permission from other heirs of the photographer,
would it be possible to release them under the GFDL or cc by sa? If they
were taken by, say, your grandfather, and there is nothing in his will
dealing with "other stuff", would you have to get permission from all of his
surviving children, or their heirs (if the children are deceased)? I'm
assuming here that the photographs are otherwise unpublished, and were taken
recently enough/the person was alive recently enough that they would still
be covered by copyright.
I'm assuming that you are talking about US law. In some other places
photographs have a shorter copyright life than texts. In the US now
these photographs should follow the manuscript and fall into the public
domain 70 years after the photographer's death unless they have
previously been published. If you have the survivor rights you can
license them in any way that you want. You can probably also do it
alone if the rights are shared. Fortunately for me, my paternal
grandfather (who died in 1948) left nothing copyrightable; he had 16
children (now all dead) and 48 grandchildren, many of whom are now dead;
one of his daughters was a nun who would have taken a vow of poverty and
made the church her heirs. To the best of my knowledge, he did not have
a will. Many of his deceased offspring did not have wills, and lived in
different jurisdictions. There are times when the decision that one
makes must be guided by practicality rather than an overstrict adherence
to the letter of the law.
It is rare for persons who are not published to think of copyrights.
Most wills, however, do have a residual clause for anything that is not
otherwise specified, and copyrights would be transferred along with
other things. If the will is defective in that way the law of intestate
succession where he lived would apply. More problematic would be a box
of family snapshots where you cannot determine who took which picture.