Damn! We kind of suspect but here we go, that's what is going on "in the shadows". Now we're kicking into serious royal/noble politics multi-way power struggle backstabbing games, with a coup against the GGF being enacted under their noses. Great stuff. And for Kate, both risk and opportunity, nothing like the chaos of that to give an underdog chances they would never get otherwise.
Still to be seem what Anthony/Christopher's goal behind it is too. Just seize power themselves? Do they see it as the only way to enact reform? See value in protecting those who exist and want a balance, even if they must be ruthless about it? And Kate still has her secret wildcard as a unified-from-birth, and also the true legitimate heir of the Mirrors Family.
This is a glorious wheels within wheels tale.