The origins of FoF have shifted since its first inception last fall. As I was working through the backstory, it seemed logical that the start of FoF would have been the legal agreement between those at La Casa and their neighbors the Calling Birds to protect their land from purchase by Zandi. It is not that they did not like Zandi -- they just were not sure what "restoration" was going to mean to the area. La Casa's Protection Agreement is on the library bookshelf.
As the call of Yeesha became more pronounced, explorers began to arrive and this affected the locals. The FoF Order took on an additional philosophical character. It still protects the integrity of the land, but also helps the newcomers find their way, as well as giving them a surface respite when not in the Cavern.
It is assumed that those who entered the Cavern lived in their Reltos. When returned to the surface they would be in New Mexico. As for sneaking back down -- well, I am assuming that we all gave up our linking books. The ones on the library shelf are non-functioning copies. We do not encourage folks to break the rules or venture into unsafe areas, but if someone can "sneak" back down, that is none of our business.