Cabbage Patch is a Changeling who just wishes to live as a pony, to forget about her past and live a somewhat normal life traveling and performing with Trixie's Thespians. Fate, and a certain Princess, have other plans for her though.
The Order-naries are back in Equestria and quickly find themselves embroiled in a disturbingly familiar adventure alongside some VERY disturbingly familiar faces.
It's hard enough just being a new Queen of the Changelings: teaching the Hive new ways to live, dealing with pony politics and plundervines, staging a musical... Try doing all that while also trying to put the old, hated Queen back on the throne
The Order-naries arrive a little too late to take part in the main plot of the MLP Movie. Saving Cadance from the Storm King and making a run for the Crystal Empire by train should make for a fine substitute adventure, though.
The spirit of Harmony reveals to Twilight that a new generation of Bearers of the Elements of Harmony will be gathered soon. Nobody, not even Harmony itself, could have guessed just how soon that gathering would need to occur.