To facilitate diplomatic visa issuance, the U.S. Department of State amends the definition of "immediate family" for the Foreign Government Official nonimmigrant visa category to include, "upon authorization form the Department on a case by case basis, any other alien who is not a member of some other household, who resides regularly in the household of the principal alien, is recognized as a family member of the principal alien, and considered by the sending Government to be a member of the immediate family of the principal by qualification for diplomatic or official passport and other allowances.”
This expansion recognizes the familial status amongst unmarried adults at least for some domestic partners who qualify for diplomatic immigration status in the U.S. References to gender and marital status are excluded.