I'm thinking of using these Yuan Yuan miniatures as Varangian Guard: I don't know why, but when I see them together the names of Terence and Bud come to mind :) The fact is that as Guardia Varega the jet on the back makes no sense and simply removing it seems a bit bland, do you think any small transformation that can be done?
not sure what parts are separated on the sculpts, but you could grab the packs from a mormaer or highlander rifle to bring the varangians in line with the Ariadna aesthetic. i don't recall any of the o12 sculpts having separate packs. but taking the ragik or bashi jet packs and clipping the wings could also work.
The Red Veil Yuan Yuan doesn't have a thruster so you can just remove the wings and fill in the hole for them.
The back of the Fat YY is just a big hole that can be easily filled. Also a good place to attach a weapon.