I've got four of them, well, two baronesses, with their "baron consorts" and two barons, with their "baroness consorts". It happened after I managed to get under nine layers of aquifer, so I just dug them their excellent bedrooms, mausoleums, offices and dining rooms and left them to do what they do, which generally is mandate things. I was amused by the fact that there's only one champion, and eight examples of nobility. Shouldn't they all have their own Champions?
Anyhow, more recently, all four of them got their duchy. More armour and weapon racks in their offices and so on (they want three of each, for each of them) and I put a whole bunch of statuary in their tombs (Which are covered in bone decorations from my beginner bonecrafter, he's getting better, but he's not there yet...) and one of them has the artifact featherwood bed in their bedroom, another an artifact cabinet in theirs, and a third an artifact armour rack which was a pleasant surprise what with needing so many of the damn things...
I've put the barons and baronesses into the military (with the Champion as their commander heheheh) but frankly, if they do die (Unfortunate accident, or forgotten beast, anything is possible) their descendants are here in the fort: They'll just inherit and the problem will continue. So I've just learned to live with them.