In the early 1950s the airport was served by the original Frontier Airlines (1950-1986) which flew DC-3's on a route from El Paso to Phoenix that included stops at Las Cruces, Deming, and Lordsburg, NM as well as Clifton, Safford, and Tucson, AZ.
A protected group is a group of people qualified for special protection by a law, policy, or similar authority. In the United States, the term is frequently used in connection with employees and employment.
In the case of a group trust, any person who had a legal interest in the assets protected by the trust would, I suppose, be considered a member, although that term is unusual. Hope this helps. Oh, and no one can be a trustee and not know it-there's paperwork involved.