I remember ages and ages ago (before I dropped Daja and brought her back), I was thinking of her doing some basic blacksmithing classes, for the people at engineering and whatnot, so that's something we could do if there's enough interest. Though in terms of advanced skills, Daja would probably only take on a couple of apprentices at most (and maybe delegate them to teaching the newbies the core skills.)

Structure wise...well, they're not really an actual Department (if anything they operate more like private business owners), but if they were Daja would probably be Head considering that she's a more experienced smith than Hiccup. Though maybe it might make sense for them to become an official Department? While Daja's part of Engineering, she actually spends most of her time in her forge, and just periodically goes to see what Engineering needs.