The first witch we fought got duplicated at one point due to a familiar running off and growing into a full witch. If, somehow, we manage to restore them back to MG-status, would there be two magical girls? Do the two duplicate witches have the same memory/soul? Or is one just the same soul with the same personality but somehow no memories?
Oh boy, metaphysical mechanics and world-building that will likely never be relevant, my favorite!
Okay, so for one thing it's a strong likelihood that neither Witch was the original--most Witches don't end up producing duplicates, but the ones that do end up with the duplicates producing their own duplicates, and so on.
Physically, assuming it's possible to examine a Grief Seed and recreate the magical girl's physical body without already knowing what she looked like, it's safe to assume that the grown-up familiar would give you a duplicate of the original girl. Whether it would be a perfect clone or just very similar might depend on what the hypothetical de-witching method actually entails.
By the rules I'm using, familiars are created by the Witch splitting off a piece of her own soul, which carries the personality, memories, and mental state along with, so the duplicate Witches would certainly retain some aspects of the original. The familiars can grow up and the Witch can replace the missing bits by absorbing soul fragments--usually taken from mundane humans who die inside the barrier, but stray familiars or even weaker Witches can be overpowered and absorbed as well.
What exactly that absorption does probably depends on the individual Witch: A scavenger-minded Witch would probably just carelessly glom it all together and lose her original identity in the process. A more predatory Witch--like many found in central Tokyo--would effectively "digest" the soul fragments, wiping clean any trace of the victim and strengthening the Witch's own identity. Lorelei, the conglomerate Witch that Yui fought, was kind of a mixture; anything she could glom together safely she did, while the rest she converted directly into tightly-controlled, very powerful familiars which she never permitted out of her barrier.
In the cases where the Witch's identity ends up diluted, the same would be true of a de-witched meguca, regardless of whether she was the "original". In that case, aspects of the victims who were absorbed would be mixed in.
tl;dr Depending on the individual Witch, anything from a bunch of perfect clones with identical personalities and matching memories to a bunch of quasi-siblings whose personalities on average tend to match the original girl and each have their own set of jumbled, self-contradictory memories from multiple people.
Of course, that's all assuming the hypothetical de-witching process works as well as it possibly can and doesn't create additional problems of its own.
Also, what does "supporting" magical girls require? You mentioned emotional support and I guess grief seeds obviously, but what else would only allow for ~30-40 MGs to be supported in Nagamioka? We seem to have harvested quite a few seeds in our short week and I think I remember one of our clairvoyants mentioned there still being "lots of witches", and you also mention baseline maintenance corruption being too low to bother keeping track of in the informational mechanics post. Is it because the 30-40 number includes things like grief-inducing events, grief spiraling, potentially large expenditures in difficult witch fights, and the need for MGs to defend themselves against other MGs too? I guess the ease with which Yui harvested seeds solo is really not the norm and thus we're able to build up a huge stockpile through killing witches kinda efficiently?
Well, the active Witch population in Nagamioka is currently 2-3 times as dense as it would normally be, with the capacity of Grief Seeds dropped also being larger than usual. That will stop being the case in the reasonably near future.
The average capacity assumes they're using magic to hunt and maybe skirmishing a bit, but nothing really major; the minimum baseline use for most meguca if they're not actively using magic is around two typical Grief Seeds per month. Obviously more for girls with permanently active magic like Chizuka, Minami, and Kaede.
Obviously, the number of meguca an area can support will be higher by using dedicated Witch-hunting teams designed to minimize corruption generated per Grief Seed obtained and keeping magical girls suited to pure support or anti-meguca combat out of Witch barriers entirely.
Given the standard population dynamics it sounds like the inevitable state of any major metropolis is to locally attain enough witches for a Walpurginacht so long as QB is aggressively contracting, and it'd work GREAT right until you approach the phase transition of a city into a walpy, simply because theres so many people that you don't even need magical girls to witch, the familiars can pick off enough people to form a sustainable witch population.
QB likes running their economic systems hot. No surprise
Eh, doesn't work if familiars get eaten too quickly. Hunter Witches grow linearly and while they can become terrifyingly powerful, there's a big gap between "actively useful to bunnycat" and "detrimental enough to bunnycat that removal is necessary."
Actually creating something like the true Walpurgisnacht is thankfully rare, because while it requires the right kind of Witch or Witches to form the "core" once the process starts it can grow exponentially.
in any case, the inner bits of Tokyo have been a net loss for Kyubey for the past decade or two and the bunnycats are actively trying to arrange for a clean sweep of the area to get
all the established Witches out. It's not presently urgent enough to risk mass casualties or devote dedicated resources, but is a moderately likely side benefit of other stuff they're doing.
To list out girls in Nagamioka right now:
I'm pretty sure you wanted "Himari", not "Hitomi". Himari and Maiko did have a teammate by that name, but she witched out years ago.
Also, Tomo is clearly a friend of JUSTICE, c'mon.
