The most remarkable aspect of pteridophyte nomenclature is how unsettled it is. There is little agreement about what constitutes a valid fern family. It seems as though every attempt to lay out a rational approach has led to a different set of circumscribed families and genera. Just look at all the abandoned genera in the list of Latin Names. It might even be said the fern families provide a better guide to pteridologists than to pteridophytes.
The Flora of North America in a chapter, Pteridophytes of North America, by Warren H. Wagner, Jr. and Alan R. Smith, lays out the problems in a section titled Classification---The Higher Ranks. One can sympathize with the difficulties, but still be dismayed by a lack of clarity or the provision of useful guidelines to identification.
So be it. Well, we need something in the way of classification; this site has chosen the FNA as its principal standard. With exceptions.
Here are the exceptions:
All in all, it is probably practical for the fern enthusiast to regard the fern families with a grain of salt, and focus on the genera and species directly. It might also be noted that this is far from heretical; the major fern horticultural references downplay or ignore the families.