Merceny clans are auto recruited by enemy kings magically. If you manage to find the LEADER of one clan who ISN'T working, you might be able to hire them but they will be gone in a few days.
The player clan doesn't seem to work well after a while, none of my sons or nephews were able to have 4 children and I think it was more like 1 or 2.
Marriage offers also don't come often enough and you often are looking at at "????" for what is being offered.
NPC lords would offer you 60 year old widows to your 18 year old son, because well Bannerlord is half coded and half not.
My NPC clans were so awful, with 15 clans it was VERY lucky if I had 2 mediocre armies formed besides mine only clan member army, they never formed an army like enemy factions did meaning stacks of 1500-2000.
Of course also native clans are having children and such so, it seems like there is almost twice as many lords as in the start of the game now.
For some reason it's not useful for the player faction, at least for me they do nothing, while NPC factions send everyone out to raid.
Force to make the choice of giving up 50 prisoners and making peace for a deal that's only going to last 5 days max or paying over 1000 influence.
Peace deals are just awful absolutely broken things, just as the voting system in general is just garbage.
Rebel clans are poorly conceived balance killers.
Cities in the no mans land end up with like 1000 prosperity and never recover because the AI doesn't invest/garrison it .
Poor, fiefless clans with high relationship cannot be converted at some point, I tried several and they just flat refuse, I own half the map but have something
like 20% of the available lords.