As used in this chapter:
(1) "Child" includes stepchildren, legally adopted children, posthumous children and recognized children born out of wedlock, but does not include married children unless actually dependent;
(2) "Brother" and "sister" includes stepbrothers, stepsisters and brothers and sisters of the half blood or by adoption, but excludes married brothers or sisters unless actually dependent;
(3) "Grandchild" includes children of adopted children or stepchildren, but excludes stepchildren of children or of adopted children and married children;
(4) "Parent" includes stepparents and parents by adoption; and (5) "Adopted" and "adoption" include cases where the persons are legally adopted.