In case anyone wants to know where to find the New Slave Girls:
1. Urchin - She was already in the game and is available after encountering the end of day domestic Event involving a group of Urchin Girls coming and taking your rations. It's random (so may the RNG gods bless you) and you essentially have to ignore it (not clicking the exterminate button) 4-5 times, then she'll appear in Red Haven
2. Ex-Arena Champion (27 yo) - She's technically not part of Mai-Lynn's questline, she's a bounty you can take at the Kahill Outpost in The Goat's Toe tavern (Click the "Look for Job" button and select the one called "Bounty"). Her encounter will then be unlocked around the Outpost
3. Akira Ito - Someone mentioned it before, but she is encountered in the final group of Rogue Space Marines in Kacey's Park with the Space Hulk, is a tough fight, so prepare well
4. Zenobia & Luckie - Both are encountered during the same mission "The Ring" which you can start by talking to the store owner of Haruki's Store in Raikan and ask if he needs any help. Be aware however that you either need to have 10,000 influence or defeat all of the Black Scorpions in Raikan (The Black Scorpions fight is tough, but I recommend you try to do so as it'll unlock an Upgradable PoI for your growing empire). To get Zenobia, you need to attack the group you encounter in the area where Haruki sends you, she'll be labeled as "Cyber Girl" during the fight. Luckie is who you'll encounter last for the mission, and you can invite her to live with you if you have the space. Luckie is her nickname and she'll be given a randomly generated name when you invite her to be your slave.
Hope this helps, good luck out there Space Slavers!