User blog comment:B214/Question and Answers 6/@comment-187.180.176.223-20190619153726/@comment-10330822-20190709072419

I don't think that's how it works, because the 72 Pillars aren't just the upper-class nobles, they cover all the nobility as a whole. Some are Dukes, Princes, Barons, Earls. In which case, if say, House Gremory, which is a Duke, made a subordinate house, a peerage, then they would hold station with the other houses, like Earls or Viscounts, which is a no-go. Its not explained whether they can form houses, true, but its made pretty clear that they'd rather the 72 Pillars go extinct than to compromise by adding mixed-races into the pyramid, in any form. After all, as Zekram pointed out, blood purity is everything. If a house is thrown out just for losing pureblood status, they'd never accept mixed-blood into the pyramid unless drastic change occured. To me that makes it clear they are not given the ability to form peerages with houses.

Of course you can form a family, whatever, but those families wouldn't have any real status or power, your just the family of this one powerful devil, nothing more. The Ultimate-Class Devils are given land to rule, but no real station, they are just like land lords.

So yeah, you can form House Rosenkreutz, but it wouldn't mean anything, they family wouldn't have any station, it's just be another devil family.