I assume that you must be referring to James Fenimore Cooper's "The
Leatherstocking Tales." I don't think that this is the "brother" which
your mother may have thought him to be. One of his books which recently
became popular when made into a major motion picture was "The Last of the
Mohicans." This should give you some clue as to the perspective of James
F. Cooper with regard to indigenes.
I'd look elsewhere if I were you; and I'd advise not advertising any
relation to this man, should it actually be true. One could hope otherwise.
Sincerely,
don Adan Cristobal largo