The family at the time consisted of Xavier Cromley and his wife, Gwyneth Cromley (Whom had both, before the mysterious decree, remained last-nameless like all peoples. Their only previous designation of family being crested flags, deeply unhygienic tattoos, and ritual scarring.) and their four children, Daulton, Rosemary, Jasmine, and Dulcimer (Who, to the dismay of his parents, never learned to play this lovely instrument.). The family very much enjoyed their new title. So much so that, once the children were old enough to marry, there appeared previously unforeseen problems.
The hooded society, speaking through the whispers of unhooded people, decreed that females should take the name of their male mates when marriage was assumed. This, of course, made sense to many. But, Rosemary and Jasmine had grown attached to the Cromley name and feared they would forever be torn from the only last name they had ever known (Though, they would still have a crested flag, a deeply unhygienic tattoo, and a ritual scar to prove their inclusion in the Cromley namesake.). Together with Xavier, Gwyneth, Daulton, and Dulcimer, it was decided that whomever the girls in the Cromley clan should marry they would take on both names. This is how Rosemary Cromley became Rosemary Cromley-O'Dowd and Jasmine Cromley became Jasmine Cromley-Bailey.
The method worked well and continued through all generations with the added disclaimer that all descendants of Cromley females would take on the Cromley name as well. Most understandably, this was done with ease for the first few generations. It was only in the later ones, when a Cromley descendant's signature took the whole of two pages, that this, too, became ridiculous. It should be noted that descendants of male Cromleys also eventually adopted the use of keeping all previous namesakes in their name. So that any descendant of a Cromley would have a name like this: Jonathan Cromley-O'Dowd-Fitzgerald-Leary-Murphy-Picadillo-Cleveland-Jennings-Grover-Janus-Salsbury-Brown-Benedict-Ferdinand-Sandwich-Glutz-Panagan-Lydigg-Goerthe-Pan-Fullerton-Pulaski-Hanning-O'Fitz-Fitz-Hague-Iacocca-Dill-Washington-Borque-Ellis-Garcia-Rodriguez-Fisher This is the actual name of one of Allister's Great Uncles.
Allister's mother and father were the first to note this ridiculousness. They resolved it simply. Each of their children, at the ripe age of six months, was placed by a listing of all the last names tangled in the branches of their family tree. Whichever the baby lingered to, be it by point or kick of foot, this would be their last name. The remaining last names would not be forgotten, however. For a time, it was thought a smaller, more hygienic tattoo would be convenient. But, hygienic or not, tattoos proved difficult to administer to six month old babies. Thus, the names were collected and given to each child in a tiny book that fit in the smallest of pockets, so that their namesakes could be with them always.