Ishgardian Nobility.

[Kauthryn]

Hi, I'm aware of the fact there are four great houses that are extant, but does this mean that the four great houses equate the upper peerage with lesser houses serving beneath them?

In other words, to put it in a kind of A Song of Ice and Fire terminology, are the Fortemps like the Starks and then do they have Boltons, Karstarks, Umbers, Manderlys, etc beneath them? Or is Ishgardian nobility only defined by the major houses?