W. Va. Code § 44-10-1: Testamentary guardians.

Every father or mother, may, by last will and testament, appoint a guardian for his or her child, born or to be born, and for such time during its infancy as he or she may direct. Where both father and mother have so appointed guardians, only that guardian who is the appointee of the parent last living shall be entitled to the custody of the person of such child.