Immediate family. The spouse, natural parent, child and sibling, adopted child and adoptive parent, stepparent, stepchild, grandparent, grandchild, stepbrother and stepsister, father-in-law, mother-in-law of the beneficiary, or provider, as appropriate. For purposes of this definition only, to determine who may render services to a beneficiary, the step-relationship continues to exist even if the marriage upon which the relationship is based terminates through divorce or death of one of the parents.
32 CFR § 199.2
General. In an effort to be as specific as possible as to the word and intent of CHAMPUS, the following definitions have been developed. While many of the definitions are general and some assign meaning to relatively common terms within the health insurance environment, others are applicable only to CHAMPUS; however, they all appear in this part solely for the purpose of the Program. Except when otherwise specified, the definitions in this section apply generally throughout this part.