VaranisArano wrote: »Check out the UESP wiki info on the NPCs in each House in Morrowind. It won't necessarily tell you the rank of a clan, but you can figure out common clan names from that, especially if you cross-reference names on ancestral tombs or common names as listed here: https://en.uesp.net/wiki/Lore:Dunmer_Names
For example, looking at the list of members of House Redoran here: https://en.m.uesp.net/wiki/Morrowind:House_Redoran
Aside from the Councilors' families, we see a couple duplicate names like: Andrano, Omalen, Indrano, Llervu, Retheran, etc.
Another method is to use names that appear in multiple games. For example, an NPC in TES 3 House Telvanni has the last name "Maryon", a last name that Skyrim reuses for the Dunmer Brelyna Maryon in the College questline.
Cygemai_Hlervu wrote: »There is a quest on Vvardenfell to help librarian Bradyn to find the Lost Library of Andule. That library contains the information on genealogies of the Great Houses. A player as I recall has no way to read those books but in order to find them a player has to take rubbings from the 30 ancestral tombs. Each tomb has a family name on it and a crest of one of the Great Houses engraved on it. For example, the Hlervu Ancestral Tomb located south of the Holamayan Monastery is marked with a symbol of the Great House Telvanni. But if it makes any sense to your in terms of RP, keep in mind that the Releth Ancestral Tomb is also a Telvanni one with the House crest on it in spite of the fact that the Releth family is also a noble family of House Redoran. Maybe this will help you somehow.
I'm not certain, but I got the impression that the families that were not the central ones of the Great Houses might have members in allegiance to more than one. That is, a family might divide its loyalties between more than one Great House, especially if they live on a border. Mercenaries may hire out to the highest bidder, and switch sides with the tides, while remaining as a family group.
So it may not be a simple hierarchy, as you imply.