In general, I'm pretty sure we cannot change the sets except at indicated time intervals, because it would cause confusion at this point if we were to change them around like that and some people went uninformed. I believe @
Amazing Ampharos
said something about this being updated every half-year, based on whatever further discussion goes on in the character specific boards. In the case of Mii Gunner, however we might be able to accommodate Chibo's request on the premise that it only really requires additions to the project, rather than changes, and that would ultimately cause less confusion, of course.
I would say to add in Chibo's requested set of 1312, as well as the other two variants of DownB, giving Gunner a total 21 sets of:
3122, 3121, 3123, 3112, 3111, 3113, 3322, 3321, 3323, 3312, 3311, 3313, 1122, 1121, 1123, 1312, 1311, 1313, 3132, 3131, 3133
Of course, this would have to be approved by Amphy before it actually becomes official. What do you say, then?