Oh... It's possible.
A LOT of stuff is possible in the new caste system.
In fact, this caste system seems to have almost no rails built into it whatsoever, and you can do some pretty crazy stuff I never expected I'd be able to get away with.
Continuing the last test, I found that there is actually a bug in the way that creatures are born in castes. My elf cows gave birth to elf calves... but some of these calves are actually
real elves, but they are treated as "calves" from their mother's caste.
... In other words, what I believe is happening is that until adulthood, the baby takes on the properties of its
mother's caste, including the length of its childhood (in this case, [CHILD:1]).
My (U)nits menu split off four of the elf calves into the same position on the units screen that is normally occupied by children of my own caste, had personalities described in their detailed view like a normal dwarf of my civ, and generally behaved as if they were a dwarf of my civ for all game purposes.
In other news, because I didn't bother to alter my dwarves since the last test, I still had unintelligent male dwarves, which turned out to be able to marry female dwarves... so I had the blushing bride turned into a butcher, and had her butcher her own husband... then adopt some vultures I had bought from the elven caravan as pets.
Why choose which is worse? Milk your husband, then butcher him, and roast his flesh in his own milk as a sauce!
... yeah, this game is getting pretty weird.
oh look! My garbage heap has "Peasant Nervous Tissue"
Butchering my elf bulls (leaving one alive to stud) produced no effect on my elven children who had actual personalities, and were tracked as psuedo-actual-dwarves. In fact, they were "Quite Content" with no tracking of their happy thoughts at all.
I think this is because they are still tracked as being their mother's caste.
Oh, and the dwarf meat and skin went to my stockpiles, but the elf meat and skin (because the elf bulls are INTELLIGENT) went to the graveyard... heh...
One of my unintelligent male dwarves became very unhappy (but didn't actually tantrum) when I butchered all the peasants.
There seems to be a crash-to-desktop bug related to dwarf fat, however, as looking at globs in the stocks menu will... well, crash-to-desktop.
My lamia are naked. This seems to be a problem with having a non-bipedal frame. Yes, I know for some, having naked women
running slithering around would be "a feature, not a bug", but it's fairly annoying.
If I put them in the military, I can force them to wear things... but it seems difficult, and my lamia seems to keep dropping equipment like helmets after she's put them on...
On the other hand, one of them is wearing iron greaves...
Finally made it through... OK, after a full year, my "true elf" elf calves are not growing into an adult, so they are simply bypassing the baby stage because of their mother, not their full adolesence