It was a guess, not my fault if it matches real history. I could spoiler tag it if you really want. Just wondering what kind of soldiers would control the battlefront if she were to take over it. Probably borrow Qin units from other factions, but obviously they wouldnt help her if she rebels. So maybe she has her own loyal soldiers? But we've never seen them so it'd be interesting to see them for the first time.
The vital stronghold strategy was mentioned ages ago, and the queen's move to obtain Sanyou/whereever is mentioned in 402.