I havent seen one with slavery, but mind control seems like something similar.
Dark Magic is about mind control, there is a point when both your mother and sister are totally corrupted:
https://f95zone.to/threads/dark-magic-v0-17-1-f-lord.18418/
Glassix - a sandbox, where you can make anyone into a fuckdoll even in public, Mom, Sis, Teachers, Store workers...
https://f95zone.to/threads/glassix-v1-0-1-public-gaweb-studio.222/
SuperPowered - grindy game, frustrating without a guide. But you can "reprogram" others behavior, mom and sis included, to fulfill your desires, act slutty, walk naked, or just to give you some money.
https://f95zone.to/threads/superpowered-v0-45-02-night-city-productions.124/
There are also great options for mom and daugter, that are not related to you, but enslaved by you:
Nympho tamer - submissive mom and daughter find a new master to serve, no grind, pure story with hot sex scenes:
https://f95zone.to/threads/nympho-tamer-v0-53-bottomless-pit.154427/
ATM Adventures - A thing of its own category. Among others, mom and daughter are forced into submission for your freeuse:
https://f95zone.to/threads/atm-adventures-v0-3-snubblr.151132/