I take no issue with merging the doll tags. Treating it as a costume modifier for either Mortis or Mutsumi makes sense to me, especially since Mutsumi as a doll in the mental world didn't actually show up past the first episode in which it appeared and situations where it's just Mutsumi doll are relatively uncommon compared to Mortis as a doll. Otherwise, I am at this point fine with however the tagging situation is solved, whether it's by the proposal in BUR #36442 or that in BUR #36357. I'd prefer the latter for the ability to flexibly negate all or any the Mortis variations in searches but either is probably going to be just okay.