baseball3792 gave by far the best explanation.

Non-rev (called Staff Traveler outside US) with family takes planning. Also, your family has to be "trained", i.e. always carry-on only and be willing to endure discomfort if long flights/red-eyes/airport lay-overs etc

We average around 20 International flights (on these airlines included in our benefits: LH, SW, AF, SN, KL, IB, SAS, AC, EK, ET, AM, OS, AV, FI, KQ, LA, LO from a total of approx 80 airlines) per year, and after 20 years seldom had to use our back-up (always have a second flight, even if it goes to a city close to where you want to be). I use Staff Travel app to check loads on other airlines.

Enjoy