The following degrees of relationship are included within the definition of “immediate relative”; (1) husband and wife; (2) natural parent, child, and sibling; (3) adopted child
and adoptive parent; (4) stepparent, stepchild, stepbrother and stepsister; (5) father-in-law,
mother-in-law, son-in-law, daughter-in-law, brother-in-law, and sister-in-law; (6)
grandparent and grandchild.
NOTE: A brother-in-law or sister-in-law relationship does not exist between a physician
(or supplier) and the spouse of his wife's (husband's) brother or sister. Neither
does a father-in-law or mother-in-law relationship exist between a physician and his
spouse's stepfather or stepmother.