This SHOULD unlock after 4 playthroughs if you do the below:
Save Gemini, She's in the bar, and doesn't need much persuasion to join, she'll give you a cool 15 grand.
At some point, you'll be told there are chicks in a bowling alley, they'll tell you their friend is at the quarantine post, go get her, on your way in, grab Gemini's jewels from her car, give the chick your zombrex, and rescue her and her friends if you feel so inclined.
Back to Gemini, she'll give you another 15 grand for her jewels, you now have 30 grand, so blow it on zombrex for your daughter.
not an overly difficult achievement, just long.