Imagine a night hag grows tired of her untrustworthy coven's backstabbing and betrayal - she decides enough is enough. Over many weeks of trial and error she eventually takes these lesser hags, ties them up, stuffs them in her Bag of Holding and uses her Plane Shift (self only) to Bytopia. She dumps them there in prisons until their alignment changes. When they are eventually / inevitably / completely good (in some neutrally or lawfully way), she brings her companions back somewhere in the Prime Material realms.
Optional Rule: Pervasive Goodwill
At the end of each long rest taken on [Bytopia], a visitor that is neither lawful good nor neutral good must make a DC 10 Wisdom saving throw. On a failed save, the creature’s alignment changes to lawful good or neutral good (whichever is closer to the creature’s current alignment). The change becomes permanent if the creature doesn’t leave the plane within 1d4 days.
[Dungeon Master's Guide, Chapter 2: Creating a Multiverse]
How would the newly minted 'extremely good' hags function? I have virtually dozens of far reaching campaign ideas on this, all of which i am afraid to use: a DM's job is to create credible, believable and somewhat RAW plot-consistent stories. This whole thing may simply be an unworkable mess, so i have come to the good folks of Stack Exchange for help.
Long story short: what happens to this coven? Could this work as a long-term Big Bad Evil-Good Group (BBEGG?) - or would they simply go thermal nuclear upon re-entry to the Prime Material?