I'm planning on taking a bunch of stuff from the module Broken Chains (not the pregnancy stuff tho, ew) and replacing the Bastards with it.
Reskinning the Garden of Chains as a section of the Pleatra. The Abandoned Qanat becomes the Westcrown sewers (so they get to go sewer crawling twice!) Instead of a cult of Lamashtu it's a cult of Mammon and they're smuggling slaves in from outside (as drug mules and to dodge taxes).
I decided that they're making the drug Ice Tears using an imprisoned Gelugon (foreshadowing for the Infernal Syndrome) that was gifted to them by the Drovenges/Melavengian. They milk the Gelugon's stinger/blood and then dilute that substance by infusing Hellspawn Tieflings, which makes them crazy ('the madness'). They can do this with other humanoids but it's lethal so they can't double up on selling them as slaves afterwards.
Ankhazu, the ghost at the end, I swapped out for the ghost of the Sister of Flies who was brought here by her followers after Vassindio Drovenge killed her and the Daughter of Flies 23 years ago. The priestess she's been possessing has instructions for destroying the Sister "just in case" hidden under her bed. It's mostly just a jar full of salt to coat her maggot-covered corpse in.
(bonus: one of my players is playing a hagblood sorcerer and she doesn't know it yet but she's a changeling meant to be the new daughter of flies, and the Sister is gonna recognize her)