From the BMW NA site, nav is listed in the "not covered" section, fwiw.
Maybe if your bro'n-law was the Ser Mgr?!
GL,mD
Accessories
Radio/cassette player, telephone,
navigation system, CD changer, or any components of those systems; non-original equipment parts, components or accessories.
Link to "What's Covered under CPO":
BMW North America
Link to "What's Not Covered under CPO":
BMW North America