I had never been keen to the idea of the heir system, not on the day of the reveal announcement, not when I played the game on release, and certainly not now. But at least, like, they have always been things they could have done to make it work in a single-player game that provides an enjoyable experience to the players.
The wanderer system, for example -- I don't get why it's so hard to just implement a system that spawn new wanderers periodically. Like, the maximum player clan size -- surely that's an easily accessible variable -- and the total number of free wanderers -- a completely trackable sum, just do that. Let's aim for 10 + maximum player clan size as the goal, subtract the number of current clan memebers and total of free wanderers from it -- perhaps even do an age check so characters who are too old are not subtracted from it -- that's the number of free wanderers that should be spawned. Then, if said value is greater than 0, simply generate a number of free wanderers between half that value (rounded up) and the total amount. Done. The game can check it every seaon or year, depending on how scarce one wants wanderers to be.
And clans -- first, don't like the heir system -- if I could I'd mod it out and have a 360-day year mod implemented too. But, if said system is to stay, Clans should have some sort of a system that force add new clan members. Just, plump, boom, pow! There, a new lord. Maybe not even a new lord, just don't show clan notables below a certain age, so there's a chance for a severely low pop clan to get one young heir force-fed to them periodically. It'd help with marriages too to have candidates of breed age -- let it be reminded the "Heir" in the "Heir System".
For players, adoption or distant relatives, I don't care, either get fresh bodies in the clan or have a minimum relative count to aim for in the player clan, and get a chance to just take them in.